Ion exchangeable glass with high crack initiation threshold

ABSTRACT

Alkali aluminosilicate glasses that are resistant to damage due to sharp impact and capable of fast ion exchange are provided. The glasses comprise at least 4 mol % P 2 O 5  and, when ion exchanged, have a Vickers indentation crack initiation load of at least about 7 kgf.

This application claims the benefit of priority under 35 USC §119 of U.S. Provisional Application Ser. No. 61/560,434 filed Nov. 16, 2011 the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND

The disclosure relates to damage resistant glasses. More particularly, the disclosure relates to damage resistant glasses that have optionally been strengthened by ion exchange. Even more particularly, the disclosure relates to damage resistant, phosphate containing glasses that have optionally been strengthened by ion exchange.

SUMMARY

Alkali aluminosilicate glasses which, when strengthened, are resistant to damage due to sharp impact and capable of fast ion exchange, are provided. The glasses comprise at least 4 mol % P₂O₅ and, when ion exchanged, have a Vickers indentation crack initiation load of at least about 7 kgf.

Accordingly, one aspect comprises an alkali aluminosilicate glass comprising at least about 4% P₂O₅, wherein the alkali aluminosilicate glass is ion exchanged to a depth of layer of at least about 10 μm, and wherein:

-   -   i. 0.6<[M₂O₃(mol %)/R_(x)O(mol %)]<1.4; or     -   ii. 1.3<[(P₂O₅+R₂O)/M₂O₃]≦2.3;         where M₂O₃=Al₂O₃+B₂O₃, R_(x)O is the sum of monovalent and         divalent cation oxides present in the alkali aluminosilicate         glass, and R₂O is the sum of monovalent cation oxides present in         the alkali aluminosilicate glass. In some embodiments, the glass         satisfies 0.6<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.4. In some         embodiments, the glass satisfies 0.6<[M₂O₃ (mol %)/R_(x)O (mol         %)]<1. In some embodiments, the glass satisfies         1.3<[(P₂O₅+R₂O)/M₂O₃]≦2.3. In some embodiments, the glass         satisfies 1.5<[(P₂O₅+R₂O)/M₂O₃]≦2.0. In some embodiments, the         alkali aluminosilicate glass further comprises less than 1 mol %         K₂O. In some embodiments, the alkali aluminosilicate glass         further comprises less than 1 mol % B₂O₃. In some embodiments,         the monovalent and divalent cation oxides are selected from the         group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO,         BaO, and ZnO. In some embodiments, the alkali aluminosilicate         glass has a potassium/sodium interdiffusion coefficient of at         least about 2.4×10⁻¹⁰ cm²/s at 410° C. In some embodiments, the         potassium/sodium interdiffusion coefficient is in a range from         about 2.4×10⁻¹⁹ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C. In         some embodiments, the glass has a compressive layer extending         from a surface of the glass to the depth of layer, and wherein         the compressive layer is under a compressive stress of at least         about 300 MPa. In some embodiments, the glass has a Vickers         indentation crack initiation load of at least about 7 kgf. In         some embodiments, the glass has a Vickers indentation crack         initiation load of at least about 12 kgf.

Another aspect comprises an alkali aluminosilicate glass comprising from about 40 mol % to about 70 mol % SiO₂; from about 11 mol % to about 25 mol % Al₂O₃; from about 4 mol % to about 15 mol % P₂O₅; and from about 13 mol % to about 25 mol % Na₂O. In some embodiments, the alkali aluminosilicate glass comprises from about 50 mol % to about 65 mol % SiO₂; from about 14 mol % to about 20 mol % Al₂O₃; from about 4 mol % to about 10 mol % P₂O₅; and from about 14 mol % to about 20 mol % Na₂O. In some embodiments, the alkali aluminosilicate glass further comprises less than 1 mol % K₂O. In some embodiments, the alkali aluminosilicate glass further comprises less than 1 mol % B₂O₃. In some embodiments, the monovalent and divalent cation oxides are selected from the group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO. In some embodiments, the alkali aluminosilicate glass has a potassium/sodium interdiffusion coefficient of at least about 2.4×10⁻¹⁰ cm²/s at 410° C. In some embodiments, the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁹ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C. In some embodiments, the glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 300 MPa. In some embodiments, the glass has a Vickers indentation crack initiation load of at least about 7 kgf. In some embodiments, the glass has a Vickers indentation crack initiation load of at least about 12 kgf.

Another aspect comprises a method of strengthening an alkali aluminosilicate glass, the method comprising providing the alkali aluminosilicate glass comprising at least about 4% P₂O₅, wherein:

-   -   i. 0.6<[M₂O₃(mol %)/R_(x)O(mol %)]<1.4; or     -   ii. 1.3<[(P₂O₅+R₂O)/M₂O₃]≦2.3;         where M₂O₃=Al₂O₃+B₂O₃, R_(x)O is the sum of monovalent and         divalent cation oxides present in the alkali aluminosilicate         glass, and R₂O is the sum of divalent cation oxides present in         the alkali aluminosilicate glass, and immersing the alkali         aluminosilicate glass in an ion exchange bath for a time period         of up to about 24 hours to form a compressive layer extending         from a surface of the alkali aluminosilicate glass to a depth of         layer of at least 10 μm. In some embodiments, the glass         satisfies 0.6<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.4. In some         embodiments, the glass satisfies 0.6<[M₂O₃ (mol %)/R_(x)O (mol         %)]<1. In some embodiments, the glass satisfies         1.3<[(P₂O₅+R₂O)/M₂O₃]≦2.3. In some embodiments, the glass         satisfies 1.5<[(P₂O₅+R₂O)/M₂O₃]≦2.0. In some embodiments, the         alkali aluminosilicate glass comprises less than 1 mol % K₂O. In         some embodiments, the alkali aluminosilicate glass comprises         less than 1 mol % B₂O₃. In some embodiments, the compressive         layer is under a compressive stress of at least about 300 MPa.         In some embodiments, the ion exchanged glass has a Vickers         indentation crack initiation load of at least about 7 kgf. In         some embodiments, the ion exchanged glass has a Vickers         indentation crack initiation load of at least about 12 kgf.

Another aspect comprises an alkali aluminosilicate glass comprising at least about 4 mol % P₂O₅, wherein [M₂O₃ (mol %)/R_(x)O (mol %)]<1.4, where M₂O₃=Al₂O₃+B₂O₃ and R_(x)O is the sum of monovalent and divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, [M₂O₃ (mol %)/R_(x)O (mol %)]<1.2. In some embodiments, [M₂O₃ (mol %)/R_(x)O (mol %)]<1. In some embodiments, the monovalent and divalent cation oxides are selected from the group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO.

In some embodiments, the alkali aluminosilicate glass comprises from about 40 mol % to about 70 mol % SiO₂; from about 11 mol % to about 25 mol % Al₂O₃; from about 4 mol % to about 15 mol % P₂O₅; and from about 13 mol % to about 25 mol % Na₂O. In other embodiments, the alkali aluminosilicate glass comprises from about 50 mol % to about 65 mol % SiO₂; from about 14 mol % to about 20 mol % Al₂O₃; from about 4 mol % to about 10 mol % P₂O₅; and from about 14 mol % to about 20 mol % Na₂O.

In some embodiments, the composition further comprises less than 1 mol % K₂O. In some embodiments, the composition further comprises about 0 mol % K₂O. In some embodiments, the composition further comprises less than 1 mol % B₂O₃. In some embodiments, the composition further comprises about 0 mol % B₂O₃.

Embodiments may be ion exchanged. In some embodiments, the glass is ion exchanged to a depth of layer of at least about 10 μm. In some embodiments, the glass is ion exchanged to a depth of layer of at least about 20 μm. In other embodiments, the glass is ion exchanged to a depth of layer of at least about 40 μm. In some embodiments, the alkali aluminosilicate glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 300 MPa. In other embodiments, the alkali aluminosilicate glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 500 MPa. In other embodiments, the alkali aluminosilicate glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 750 MPa. In some embodiments, the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 7 kgf. In still other embodiments, the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 15 kgf. In other embodiments, the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 20 kgf. In some embodiments, the alkali aluminosilicate glass has a potassium/sodium interdiffusion coefficient of at least about 2.4×10⁻¹⁰ cm²/s at 410° C. In some embodiments, the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁰ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C.

Another aspect is to provide an alkali aluminosilicate glass comprising at least about 4 mol % P₂O₅. The alkali aluminosilicate glass is ion exchanged to a depth of layer of at least about 10 μm, wherein 0.6<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.4, where M₂O₃=Al₂O₃+B₂O₃ and R_(x)O is the sum of monovalent and divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, 0.6<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.2. In some embodiments, 0.6<[M₂O₃ (mol %)/R_(x)O (mol %)]<1. In some embodiments, 0.8<[M₂O₃ (mol %)/R_(x)O (mol %)]<1. In some embodiments, the monovalent and divalent cation oxides are selected from the group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO.

In some embodiments, the alkali aluminosilicate glass comprises from about 40 mol % to about 70 mol % SiO₂; from about 11 mol % to about 25 mol % Al₂O₃; from about 4 mol % to about 15 mol % P₂O₅; and from about 13 mol % to about 25 mol % Na₂O. In other embodiments, the alkali aluminosilicate glass comprises from about 50 mol % to about 65 mol % SiO₂; from about 14 mol % to about 20 mol % Al₂O₃; from about 4 mol % to about 10 mol % P₂O₅; and from about 14 mol % to about 20 mol % Na₂O.

In some embodiments, the composition further comprises less than 1 mol % K₂O. In some embodiments, the composition further comprises about 0 mol % K₂O. In some embodiments, the composition further comprises less than 1 mol % B₂O₃. In some embodiments, the composition further comprises about 0 mol % B₂O₃.

Embodiments of the aspect may be ion exchanged. In some embodiments, the glass is ion exchanged to a depth of layer of at least about 10 μm. In some embodiments, the glass is ion exchanged to a depth of layer of at least about 20 μm. In other embodiments, the glass is ion exchanged to a depth of layer of at least about 40 μm. In some embodiments, the alkali aluminosilicate glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 300 MPa. In other embodiments, the alkali aluminosilicate glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 500 MPa. In other embodiments, the alkali aluminosilicate glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 750 MPa. In some embodiments, the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 7 kgf. In still other embodiments, the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 15 kgf. In other embodiments, the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 20 kgf. In some embodiments, the alkali aluminosilicate glass has a potassium/sodium interdiffusion coefficient of at least about 2.4×10⁻¹⁰ cm²/s at 410° C. In some embodiments, the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁰ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C.

Another aspect of the disclosure is to provide a method of strengthening an alkali aluminosilicate glass. The method comprises: providing the alkali aluminosilicate glass, the alkali aluminosilicate glass comprising at least about 4 mol % P₂O₅, wherein:

-   -   i. 0.6<[M₂O₃(mol %)/R_(x)O(mol %)]<1.4; or     -   ii. 1.3<[(P₂O₅+R₂O)/M₂O₃]≦2.3;         where M₂O₃=Al₂O₃+B₂O₃, R_(x)O is the sum of monovalent and         divalent cation oxides present in the alkali aluminosilicate         glass, and R₂O is the sum of divalent cation oxides present in         the alkali aluminosilicate glass, and immersing the alkali         aluminosilicate glass in an ion exchange bath for a time period         of up to about 24 hours to form a compressive layer extending         from a surface of the alkali aluminosilicate glass to a depth of         layer of at least 10 μm. In some embodiments, the glass         satisfies 0.6<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.4. In some         embodiments, the glass satisfies 0.6<[M₂O₃ (mol %)/R_(x)O (mol         %)]<1. In some embodiments, the glass satisfies         1.3<[(P₂O₅+R₂O)/M₂O₃]≦2.3. In some embodiments, the glass         satisfies 1.5<[(P₂O₅+R₂O)/M₂O₃]≦2.0. In some embodiments, the         alkali aluminosilicate glass comprises less than 1 mol % K₂O. In         some embodiments, the alkali aluminosilicate glass comprises         less than 1 mol % B₂O₃. In some embodiments, the compressive         layer is under a compressive stress of at least about 300 MPa.         In some embodiments, the ion exchanged glass has a Vickers         indentation crack initiation load of at least about 7 kgf. In         some embodiments, the ion exchanged glass has a Vickers         indentation crack initiation load of at least about 12 kgf. In         some embodiments, the compressive layer extends from a surface         to a depth of layer of at least 70 μm.

In some embodiments, the alkali aluminosilicate glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 300 MPa. In other embodiments, the alkali aluminosilicate glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 500 MPa. In other embodiments, the alkali aluminosilicate glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 750 MPa. In some embodiments, the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 7 kgf. In still other embodiments, the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 15 kgf. In other embodiments, the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 20 kgf. In some embodiments, the alkali aluminosilicate glass has a potassium/sodium interdiffusion coefficient of at least about 2.4×10⁻¹⁰ cm²/s at 410° C. In some embodiments, the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁰ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C.

In some embodiments, the alkali aluminosilicate glass used in the method comprises monovalent and divalent cation oxides selected from the group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO.

In some embodiments, the alkali aluminosilicate glass used in the method comprises from about 40 mol % to about 70 mol % SiO₂; from about 11 mol % to about 25 mol % Al₂O₃; from about 4 mol % to about 15 mol % P₂O₅; and from about 13 mol % to about 25 mol % Na₂O. In other embodiments, the alkali aluminosilicate glass used in the method comprises from about 50 mol % to about 65 mol % SiO₂; from about 14 mol % to about 20 mol % Al₂O₃; from about 4 mol % to about 10 mol % P₂O₅; and from about 14 mol % to about 20 mol % Na₂O.

In some embodiments, the composition used in the method further comprises less than 1 mol % K₂O. In some embodiments, the composition used in the method further comprises about 0 mol % K₂O. In some embodiments, the composition used in the method further comprises less than 1 mol % B₂O₃. In some embodiments, the composition used in the method further comprises about 0 mol % B₂O₃.

These and other aspects, advantages, and salient features will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a glass sheet strengthened by ion exchange; and

FIG. 2 is a plot of depth of layer as a function of compressive stress for 0.7 mm thick samples that were annealed at 700° C. and ion exchanged in a molten KNO₃ salt bath at 410° C.

DETAILED DESCRIPTION

Disclosed are materials, compounds, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for, or are embodiments of the disclosed method and compositions. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds may not be explicitly disclosed, each is specifically contemplated and described herein.

Thus, if a class of substituents A, B, and C are disclosed as well as a class of substituents D, E, and F, and an example of a combination embodiment, A-D is disclosed, then each is individually and collectively contemplated. Thus, in this example, each of the combinations A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C—F are specifically contemplated and should be considered disclosed from disclosure of A, B, and/or C; D, E, and/or F; and the example combination A-D. Likewise, any subset or combination of these is also specifically contemplated and disclosed. Thus, for example, the sub-group of A-E, B-F, and C-E are specifically contemplated and should be considered disclosed from disclosure of A, B, and/or C; D, E, and/or F; and the example combination A-D. This concept applies to all aspects of this disclosure including, but not limited to any components of the compositions and steps in methods of making and using the disclosed compositions. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the disclosed methods, and that each such combination is specifically contemplated and should be considered disclosed.

In addition, whenever a group is described as comprising at least one of a group of elements and combinations thereof, it is understood that the group may comprise, consist essentially of, or consist of any number of those elements recited, either individually or in combination with each other. Similarly, whenever a group is described as consisting of at least one of a group of elements or combinations thereof, it is understood that the group may consist of any number of those elements recited, either individually or in combination with each other.

Moreover, where a range of numerical values is recited herein, comprising upper and lower values, unless otherwise stated in specific circumstances, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the disclosure be limited to the specific values recited when defining a range. Further, when an amount, concentration, or other value or parameter is given as a range, one or more preferred ranges or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether such pairs are separately disclosed. Finally, when the term “about” is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to.

As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about” or “approximate” whether or not expressly stated to be such.

The term “or”, as used herein, is inclusive; more specifically, the phrase “A or B” means “A, B, or both A and B”. Exclusive “or” is designated herein by terms such as “either A or B” and “one of A or B”, for example.

The indefinite articles “a” and “an” are employed to describe elements and components of embodiments. The use of these articles means that one or at least one of these elements or components is present. Although these articles are conventionally employed to signify that the modified noun is a singular noun, as used herein the articles “a” and “an” also include the plural, unless otherwise stated in specific instances. Similarly, the definite article “the”, as used herein, also signifies that the modified noun may be singular or plural, again unless otherwise stated in specific instances.

For the purposes of describing the embodiments, it is noted that reference herein to a variable being a “function” of a parameter or another variable is not intended to denote that the variable is exclusively a function of the listed parameter or variable. Rather, reference herein to a variable that is a “function” of a listed parameter is intended to be open ended such that the variable may be a function of a single parameter or a plurality of parameters. It is also understood that, unless otherwise specified, terms such as “top,” “bottom,” “outward,” “inward,” and the like are words of convenience and are not to be construed as limiting terms.

It is noted that terms like “preferably,” “commonly,” and “typically,” when utilized herein, are not utilized to limit the scope or to imply that certain features are critical, essential, or even important to the structure or function of the embodiments described. Rather, these terms are merely intended to identify particular aspects of an embodiment or to emphasize alternative or additional features that may or may not be utilized in a particular embodiment.

For the purposes of describing and defining embodiments it is noted that the terms “substantially” and “approximately” are utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The terms “substantially” and “approximately” are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

It is noted that one or more of the claims may utilize the term “wherein” as a transitional phrase. For the purposes of defining embodiments, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.”

As a result of the raw materials and/or equipment used to produce the glass composition, certain impurities or components that are not intentionally added, can be present in the final glass composition. Such materials are present in the glass composition in minor amounts and are referred to herein as “tramp materials.”

As used herein, a glass composition having 0 wt % or mol % of a compound is defined as meaning that the compound, molecule, or element was not purposefully added to the composition, but the composition may still comprise the compound, typically in tramp or trace amounts. Similarly, “sodium-free,” “alkali-free,” “potassium-free” or the like are defined to mean that the compound, molecule, or element was not purposefully added to the composition, but the composition may still comprise sodium, alkali, or potassium, but in approximately tramp or trace amounts. Unless otherwise specified, the concentrations of all constituents recited herein are expressed in terms of mole percent (mol %).

Vickers indentation cracking threshold measurements described herein are performed by applying and then removing an indentation load to the glass surface at a rate of 0.2 mm/min. The maximum indentation load is held for 10 seconds. The indentation cracking threshold is defined at the indentation load at which 50% of 10 indents exhibit any number of radial/median cracks emanating from the corners of the indent impression. The maximum load is increased until the threshold is met for a given glass composition. All indentation measurements are performed at room temperature in 50% relative humidity.

Referring to the drawings in general and to FIG. 1 in particular, it will be understood that the illustrations are for the purpose of describing particular embodiments and are not intended to limit the disclosure or appended claims thereto. The drawings are not necessarily to scale, and certain features and certain views of the drawings may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.

Chemically strengthened alkali aluminosilicate glasses having high damage resistance (i.e., having Vickers cracking thresholds of greater than 15 kilograms force (kgf), and, in some embodiments, greater than 20 kgf, typically have compositions that satisfy the rule [(Al₂O₃ (mol %)+B₂O₃ (mol %))/(Σmodifier oxides (mol %))]>1, where the modifier oxides include alkali and alkaline earth oxides. Such glasses have been previously described in U.S. patent application Ser. No. 12/858,490, filed Aug. 18, 2010, by Kristen L. Barefoot et al., entitled “Crack and Scratch Resistant Glass and Enclosures Made Therefrom.”

The enhanced damage resistance of P₂O₅-containing alkali aluminosilicate glasses has been previously described in U.S. Provisional Patent Application No. 61/417,941, filed on Nov. 30, 2010, by Dana Craig Bookbinder et al., entitled “Ion Exchangeable Glass with Deep Compressive Layer and High Modulus.” The glasses described therein contain phosphate batched with Al₂O₃ and B₂O₃ to form AlPO₄ and BPO₄, respectively, and follow the composition rule

-   -   0.75≦[(P₂O₅(mol %)+R₂O(mol %))/M₂O₃(mol %)]≦1.3,         where M₂O₃=Al₂O₃+B₂O₃.

Described herein are embodiments comprising P₂O₅-containing alkali aluminosilicate glasses and articles made therefrom which, when chemically strengthened by ion exchange, achieve Vickers cracking thresholds of at least about 7 kgf, 8, kgf, 9, kgf, 10, kgf, 11 kgf, 12 kgf, 13 kgf, 14 kgf, 15 kgf 16 kgf, 17 kgf, 18 kgf, 19 kgf, and, in some embodiments, at least about 20 kgf. The damage resistance of these glasses and glass articles is enhanced by the addition of at least about 4 mol % P₂O₅. In some embodiments, the damage resistance is enhanced by the addition of at least about 5 mol % P₂O₅. In some embodiments, the P₂O₅ concentration is in a range from about 4 mol % up to about 10 mol % and, in other embodiments in a range from about 4 mol % up to about 15 mol %.

Embodiments described herein generally fall outside the glasses and glass articles of the composition space described in U.S. Provisional Patent Application No. 61/417,941. In addition, the glasses described in the present disclosure nominally comprise primarily tetrahedrally coordinated phosphate (PO₄ ³⁻) groups that contain one double-bonded oxygen per tetrahedral phosphorus structural unit.

In some embodiments, ratios of M₂O₃ to ΣR_(x)O provide glasses that have advantageous melting temperatures, viscosities, and/or liquidus temperatures. Some embodiments may be described by the ratio (M₂O₃ (mol %)/ΣR_(x)O (mol %))<1.4, where M₂O₃=Al₂O₃+B₂O₃, and wherein ΣR_(x)O is the sum of monovalent and divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, the glasses and glass articles described herein comprise greater than 4 mol % P₂O₅, wherein the ratio (M₂O₃ (mol %)/ΣR_(x)O (mol %)) is less than 1.4, where M₂O₃=Al₂O₃+B₂O₃, and wherein ΣR_(x)O is the sum of monovalent and divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, the ratio of (M₂O₃ (mol %)/ΣR_(x)O (mol %)) is less than 1.0. In some embodiments, the ratio of (M₂O₃ (mol %)/ΣR_(x)O (mol %)) is less than 1.4, 1.35, 1.3, 1.25, 1.2, 1.15, 1.1, 1.05, 1.0, 0.95, 0.9, 0.85, 0.8, 0.75, or 0.7. In some embodiments, 0.6<(M₂O₃ (mol %)/R_(x)O (mol %))<1.4. In some embodiments, 0.6<(M₂O₃ (mol %)/R_(x)O (mol %))<1.2. In some embodiments, 0.6<(M₂O₃ (mol %)/R_(x)O (mol %))<1. In some embodiments, 0.8<(M₂O₃ (mol %)/R_(x)O (mol %))<1.4. In some embodiments, 0.8<(M₂O₃ (mol %)/R_(x)O (mol %))<1.2. In some embodiments, 0.8<(M₂O₃ (mol %)/R_(x)O (mol %))<1.0. In some embodiments, Y<(M₂O₃ (mol %)/R_(x)O (mol %))<Z, wherein Y is about 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, or 1.1 and X is independently about 1.4, 1.35, 1.3, 1.25, 1.2, 1.15, 1.1, 1.05, 1.0, 0.95, 0.9, 0.85, 0.8, and wherein X>Y. Such monovalent and divalent oxides include, but are not limited to, alkali metal oxides (Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O), alkaline earth oxides (MgO, CaO, SrO, BaO), and transition metal oxides such as, but not limited to, ZnO.

In some embodiments, the glasses described herein satisfy the inequality

-   -   [(Al₂O₃(mol %)+B₂O₃(mol %))/(Σmodifier oxides(mol %))]<1.0.

In some embodiments, the glasses can have sufficient P₂O₅ to allow for a glass structure wherein P₂O₅ is present in the structure rather, or in addition to, MPO₄. In some embodiments, such a structure may be described by the ratio [(P₂O₅ (mol %)+R₂O (mol %))/M₂O₃ (mol %)]>1.24, where M₂O₃=Al₂O₃+B₂O₃, P₂O₅ is 4 mol % or greater, and wherein R₂O is the sum divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, the glasses described herein comprise greater than 4 mol % P₂O₅, wherein the ratio of [(P₂O₅ (mol %)+R₂O (mol %))/M₂O₃ (mol %)] is greater than 1.24, where M₂O₃=Al₂O₃+B₂O₃, and wherein R₂O is the sum divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, the ratio of [(P₂O₅ (mol %)+R₂O (mol %))/M₂O₃ (mol %)] is greater than 1.3. In some embodiments, the ratio is 1.24≦[(P₂O₅ (mol %)+R₂O (mol %))/M₂O₃ (mol %)]≦2.8. In some embodiments, the glasses and glass articles described herein comprise greater than 4 mol % P₂O₅, and are described by the ratio

-   -   S≦[(P₂O₅(mol %)+R₂O(mol %))/M₂O₃(mol %)]≦V         wherein S is independently about 1.5, 1.45, 1.4, 1.35, 1.3,         1.25, 1.24, 1.2, or 1.15, and V is independently about 2.0,         2.05, 2.1, 2.15, 2.2, 2.25, 2.3, 2.35, 2.4, 2.45, 2.5, 2.55,         2.6, 2.65, 2.7, 2.75, or 2.8.

The alkli aluminosilicate glasses and articles described herein comprise a number of chemical components. SiO₂, an oxide involved in the formation of glass, functions to stabilize the networking structure of glass. In some embodiments, the glass composition can comprise from about 40 to about 70 mol % SiO₂. In some embodiments, the glass composition can comprise from about 50 to about 70 mol % SiO₂. In some embodiments, the glass composition can comprise from about 55 to about 65 mol % SiO₂. In some embodiments, the glass composition can comprise from about 40 to about 70 mol %, about 40 to about 65 mol %, about 40 to about 60 mol %, about 40 to about 55 mol %, about 40 to 50 mol %, about 40 to 45 mol %, 50 to about 70 mol %, about 50 to about 65 mol %, about 50 to about 60 mol %, about 50 to about 55 mol %, about 55 to about 70 mol %, about 60 to about 70 mol %, about 65 to about 70 mol %, about 55 to about 65 mol %, or about 55 to about 60 mol % SiO₂. In some embodiments, the glass composition comprises about 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, or 70 mol % SiO₂.

Al₂O₃ may provide, among other benefits, for a) maintaining the lowest possible liquidus temperature, b) lowering the expansion coefficient, or c) enhancing the strain point. In some embodiments, the glass composition can comprise from about 11 to about 25 mol % Al₂O₃. In some embodiments, the glass composition can comprise from about 14 to about 20 mol % Al₂O₃. In some embodiments, the glass composition can comprise from about 11 to about 25 mol %, about 11 to about 20 mol %, about 11 to about 18 mol %, about 11 to about 15 mol %, about 12 to about 25 mol %, about 12 to about 20 mol %, about 12 to about 18 mol %, about 12 to about 15 mol %, about 14 to about 25 mol %, about 14 to about 20 mol %, about 14 to about 18 mol %, about 14 to about 15 mol %, about 18 to about 25 mol %, about 18 to about 20 mol %, or about 20 to about 25 mol % Al₂O₃. In some embodiments, the glass composition can comprise about 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 mol % Al₂O₃.

The presence of B₂O₃ in embodiments can improve damage resistance, but may also be detrimental to compressive stress and diffusivity. The glasses described herein generally do not contain—or are free of—B₂O₃. In some embodiments, about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, or 4 mol % B₂O₃ may be present. In some embodiments, less than 4, 3, 2, or 1 mol % B₂O₃ may be present. In some embodiments, tramp B₂O₃ may be present. In some embodiments, the glass composition can comprise about 0 mol % B₂O₃. In some embodiments, the amount of B₂O₃ is 0.5 mol % or less, 0.25 mol % or less, 0.1 mol % or less, about 0.05 mol % or less, 0.001 mol % or less, 0.0005 mol % or less, or 0.0001 mol % or less. The glass compositions, according to some embodiments, are free of intentionally added B₂O₃.

It has been discovered that addition of phosphorous to the glass as P₂O₅ improves damage resistance and does not impede ion exchange. In some embodiments, the addition of phosphorous to the glass creates a structure in which silica (SiO₂ in the glass) is replaced by aluminum phosphate (AlPO₄), which consists of tetrahedrally coordinated aluminum and phosphorus and/or boron phosphate (BPO₄), which consists of tetrahedrally coordinated boron and phosphorus. The glasses described herein generally contain greater than 4 mol % P₂O₅. In some embodiments, the glass can comprise from about 4 to about 15 mol % P₂O₅. In some embodiments, the glass can comprise from about 4 to about 12 mol % P₂O₅. In some embodiments, the glass can comprise from about 4 to about 10 mol % P₂O₅. In some embodiments, the glass can comprise from about 6 to about 10 mol % P₂O₅. In some embodiments, the glass composition can comprise from about 4 to about 15 mol %, about 6 to about 15 mol %, about 8 to about 15 mol %, about 10 to about 15 mol %, about 12 to about 15 mol %, about 4 to about 12 mol %, about 4 to about 10 mol %, about 4 to about 8 mol %, about 4 to about 6 mol %, about 6 to about 12 mol %, about 6 to about 10 mol %, about 6 to about 8 mol %, about 8 to about 12 mol %, about 8 to about 10 mol %, about 10 to about 12 mol %. In some embodiments, the glass composition can comprise about 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or mol % P₂O₅.

Na₂O may be used for ion exchange in embodied glasses. In some embodiments, the glass can comprise from about 13 to about 25 mol % Na₂O. In other embodiments, the glass can comprise about 13 to about 20 mol % Na₂O. In some embodiments, the glass composition can comprise from about 13 to about 25 mol %, about 13 to about 20 mol %, about 13 to about 18 mol %, about 13 to about 15 mol %, about 15 to about 25 mol %, about 15 to about 20 mol %, about 15 to about 18 mol %, about 18 to about 25 mol %, about 18 to about 20 mol %, or about 20 to about 25 mol %. In some embodiments, the glass can comprise about 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 mol % Na₂O.

R_(x)O generally describes monovalent and divalent cation oxides present in the alkali aluminosilicate glass. The presence R_(x)O may provide advantages for ion exchange of the glass. Such monovalent and divalent oxides include, but are not limited to, alkali metal oxides (Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O), alkaline earth oxides (MgO, CaO, SrO, BaO), and transition metal oxides such as, but not limited to, ZnO. In some embodiments, the amount of R_(x)O in the composition is described by the equation (M₂O₃ (mol %)/ΣR_(x)O (mol %))<1.4. In some embodiments, the amount of R_(x)O in the composition is described by the equation (M₂O₃ (mol %)/ΣR_(x)O (mol %))<1.0. In some embodiments, the amount of R_(x)O in the composition is described by the equation 0.6<(M₂O₃ (mol %)/ΣR_(x)O (mol %))<1.4. In some embodiments, the amount of R_(x)O in the composition is described by the equation 0.6<(M₂O₃ (mol %)/ΣR_(x)O (mol %))<1.0. In some embodiments, the glass composition can comprise from about 7 to about 30 mol % Al₂O₃. In some embodiments, the glass composition can comprise from about 14 to about 25 mol % Al₂O₃. In some embodiments, the glass composition can comprise from about 7 to about 30 mol %, about 7 to about 25 mol %, about 7 to about 22 mol %, about 7 to about 20 mol %, about 7 to about 18 mol %, about 7 to about 15 mol %, about 7 to about 10 mol %, about 10 to about 30 mol %, about 10 to about 25 mol %, about 10 to about 22 mol %, about 10 to about 18 mol %, about 10 to about 15 mol %, about 15 to about 30 mol %, about 15 to about 25 mol %, about 15 to about 22 mol %, about 15 to about 18 mol %, about 18 to about 30 mol %, about 18 to about 25 mol %, about 18 to about 22 mol %, about 18 to about 20 mol %, about 20 to about 30 mol %, about 20 to about 25 mol %, about 20 to about 22 mol %, about 22 to about 30 mol %, about 22 to about 25 mol %, or about 25 to about 30 mol %. In some embodiments, the glass composition can comprise about 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 mol % R_(x)O.

M₂O₃ describes the amount of Al₂O₃ and B₂O₃ in the composition. In some embodiments, the glass composition can comprise from about 11 to about 30 mol % M₂O₃. In some embodiments, the glass composition can comprise from about 14 to about 20 mol % M₂O₃. In some embodiments, the glass composition can comprise from about 11 to about 30 mol %, about 11 to about 25 mol %, about 11 to about 20 mol %, about 11 to about 18 mol %, about 11 to about 15 mol %, about 12 to about 30 mol %, about 12 to about 25 mol %, about 12 to about 20 mol %, about 12 to about 18 mol %, about 12 to about 15 mol %, about 14 to about 30 mol %, about 14 to about 25 mol %, about 14 to about 20 mol %, about 14 to about 18 mol %, about 14 to about 15 mol %, about 18 to about 25 mol %, about 18 to about 20 mol %, or about 20 to about 25 mol % M₂O₃. In some embodiments, the glass composition can comprise about 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 mol % M₂O₃.

K₂O in some embodiments can be used for ion exchange, but can be detrimental to compressive stress. In some embodiments, the glass compositions are free of K₂O. The glass compositions are substantially K₂O-free, for example, when the content of K₂O is 0.5 mol percent or less, 0.25 mol % or less, 0.1 mol % or less, about 0.05 mol % or less, 0.001 mol % or less, 0.0005 mol % or less, or 0.0001 mol % or less. The glass sheets, according to some embodiments, are free of intentionally added sodium. In some embodiments, the glass can comprise from 0 to about 1 mol % K₂O. In other embodiments, the glass can comprise greater than 0 to about 1 mol % K₂O. In some embodiments, the glass composition can comprise from 0 to about 2 mol %, 0 to about 1.5 mol %, 0 to about 1 mol %, 0 to about 0.9 mol %, 0 to about 0.8 mol % 0 to about 0.7 mol %, 0 to about 0.6 mol %, 0 to about 0.5 mol %, 0 to about 0.4 mol %, 0 to about 0.3 mol %, 0 to about 0.2 mol %, or 0 to about 0.1 mol %. In some embodiments, the glass can comprise about 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 mol % K₂O.

Additional components can be incorporated into the glass compositions to provide additional benefits. For example, additional components can be added as fining agents (e.g., to facilitate removal of gaseous inclusions from melted batch materials used to produce the glass) and/or for other purposes. In some embodiments, the glass may comprise one or more compounds useful as ultraviolet radiation absorbers. In some embodiments, the glass can comprise 3 mol % or less TiO₂, MnO, ZnO, Nb₂O₅, MoO₃, Ta₂O₅, WO₃, ZrO₂, Y₂O₃, La₂O₃, HfO₂, CdO, SnO₂, Fe₂O₃, CeO₂, As₂O₃, Sb₂O₃, Cl, Br, or combinations thereof. In some embodiments, the glass can comprise from 0 to about 3 mol %, 0 to about 2 mol %, 0 to about 1 mol %, 0 to 0.5 mol %, 0 to 0.1 mol %, 0 to 0.05 mol %, or 0 to 0.01 mol % TiO₂, MnO, ZnO, Nb₂O₅, MoO₃, Ta₂O₅, WO₃, ZrO₂, Y₂O₃, La₂O₃, HfO₂, CdO, SnO₂, Fe₂O₃, CeO₂, As₂O₃, Sb₂O₃, Cl, Br, or combinations thereof. In some embodiments, the glass can comprise from 0 to about 3 mol %, 0 to about 2 mol %, 0 to about 1 mol %, 0 to about 0.5 mol %, 0 to about 0.1 mol %, 0 to about 0.05 mol %, or 0 to about 0.01 mol % TiO₂, CeO₂, or Fe₂O₃, or combinations thereof.

The glass composition, according to some embodiments, (e.g., any of the glasses discussed above) can include F, Cl, or Br, for example, as in the case where the glasses comprise Cl and/or Br as fining agents.

The glass composition, according to some embodiments, can comprise BaO. In certain embodiments, the glasses can comprise less than about 5, less than about 4, less than about 3, less than about 2, less than about 1, less than 0.5, or less than 0.1 mol % of BaO.

In some embodiments, the glass can be substantially free of Sb₂O₃, As₂O₃, or combinations thereof. For example, the glass can comprise 0.05 mol % or less of Sb₂O₃ or As₂O₃ or a combination thereof, the glass may comprise zero mol % of Sb₂O₃ or As₂O₃ or a combination thereof, or the glass may be, for example, free of any intentionally added Sb₂O₃, As₂O₃, or combinations thereof.

The glasses, according to some embodiments, can further comprise contaminants typically found in commercially-prepared glass. In addition, or alternatively, a variety of other oxides (e.g., TiO₂, MnO, ZnO, Nb₂O₅, MoO₃, Ta₂O₅, WO₃, ZrO₂, Y₂O₃, La₂O₃, P₂O₅, and the like) may be added, albeit with adjustments to other glass components, without compromising the melting or forming characteristics of the glass composition. In those cases where the glasses, according to some embodiments, further include such other oxide(s), each of such other oxides are typically present in an amount not exceeding about 3 mol %, about 2 mol %, or about 1 mol %, and their total combined concentration is typically less than or equal to about 5 mol %, about 4 mol %, about 3 mol %, about 2 mol %, or about 1 mol %. In some circumstances, higher amounts can be used so long as the amounts used do not place the composition outside of the ranges described above. The glasses, according to some embodiments, can also include various contaminants associated with batch materials and/or introduced into the glass by the melting, fining, and/or forming equipment used to produce the glass (e.g., ZrO₂).

In some embodiments, the alkali aluminosilicate glasses and articles described herein comprise from about 40 mol % to about 70 mol % SiO₂; from about 11 mol % to about 25 mol % Al₂O₃; from about 4 mol % to about 15 mol % P₂O₅; and from about 11 mol % to about 25 mol % Na₂O.

In some embodiments, the glass compositions have high damage resistance. In some embodiments, the glass compositions have Vickers cracking thresholds of greater than 7 kilograms force (kgf). In some embodiments, the glass compositions have Vickers cracking thresholds of greater than 12 kgf. In some embodiments, the glass compositions have Vickers cracking thresholds of greater than 15 kgf. In some embodiments, the glass compositions have Vickers cracking thresholds of greater than 20 kgf. In some embodiments, the glass compositions have Vickers cracking thresholds of greater than 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 kgf.

Non-limiting examples of embodied glasses (wherein the glass thickness is 0.7 mm) are listed in Table 1.

TABLE 1 Glass compositions and properties. Sample a b c d e f g h i j k l SiO₂ (mol %) 61 59 57 62 60 58 60 60 60 60 60 60 B₂O₃ (mol %) 0 0 0 0 0 0 0 0 0 0 0 0 Al₂O₃ (mol %) 15.5 16.5 17.5 15.5 16.5 17.5 16 16 16 16 16 16 P₂O₅ (mol %) 7 7 7 6 6 6 5 5 6 6 7 7 Na₂O (mol %) 16.5 17.5 18.5 16.5 17.5 18.5 16 16 16 16 16 16 MgO (mol %) 0 0 0 0 0 0 3 0 2 0 1 0 ZnO (mol %) 0 0 0 0 0 0 0 3 0 2 0 1 Density 2.388 2.401 2.412 2.393 2.406 2.416 (g/cm³) Molar Volume 30.41 30.43 30.47 30.01 30.03 30.08 (cm³/mol) Strain Point 615 620 625 633 638 640 (° C.) Anneal Point 675 678 682 693 697 699 (° C.) Softening 963 958 951 973 978 969 Point (° C.) T200P (° C.) 1732 1708 1683 1752 1720 1698 T35000P (° C.) 1284 1274 1260 1304 1289 1275 T160000P (° C.) 1195 1186 1176 1215 1202 1191 Liquidus 775 740 730 770 790 770 Temperature (° C.) 0.7 mm thick parts annealed 410° C., 8 hr 665 over over over over over Compressive limits limits limits limits limits Stress (MPa) of of of of of FSM FSM FSM FSM FSM 410° C., 8 hr 113 over over over over over Depth of Layer limits limits limits limits limits (μm) of of of of of FSM FSM FSM FSM FSM 410° C., 1 hr 764 806 866 805 863 922 Compressive Stress (MPa) 410° C., 1 hr 40 38 38 39 37 36 Depth of Layer (μm) 410° C., 4 hr 706 747 804 745 805 over Compressive limits Stress (MPa) of FSM 410° C., 4 hr 80 82 80 77 77 over Depth of Layer limits (microns) of FSM 410° C., 4 hr >25 >20 >20 >15 >25 >15 Vickers Crack Initiation Load (kgf) 470° C., 6 min 736 780 837 778 836 894 Compressive Stress (MPa) 470° C., 6 min 23 23 23 23 23 23 Depth of Layer (μm) (Al₂O₃ + 0.94 0.94 0.95 0.94 0.94 0.95 0.84 0.84 0.89 0.89 0.94 0.94 B₂O₃)/R_(x)O (P₂O₅ + R_(x)O)/ 1.52 1.48 1.46 1.45 1.42 1.40 1.5 1.5 1.5 1.5 1.54 1.5 M₂O₃ K⁺/Na⁺ Ion- 5.78 5.65 5.50 5.43 5.16 4.69 Exchange Interdiffusion Coefficient at 410° C. in annealed parts × 10⁻¹⁰(cm²/s)

Non-limiting examples of embodied glasses (wherein the glass thickness is 1.0 mm) are listed in Table 2 (for ion-exchange data, if no SOC is provided, the default used was 3.0 using 1.0 mm thick ion-exchanged parts).

TABLE 2 Glass compositions and properties. Example Number 1 2 3 4 5 6 7 SiO₂ in mol % 61.0 59.0 57.0 62.0 60.0 58.0 58.0 Al₂O₃ in mol % 15.5 16.5 17.5 15.5 16.5 17.5 17.4 P₂O₅ in mol % 7.0 7.0 7.0 6.0 6.0 6.0 6.1 Na₂O in mol % 16.5 17.5 18.5 16.5 17.5 18.5 18.5 MgO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.1 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 CaO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.94 0.94 0.95 0.94 0.94 0.95 0.95 (P₂O₅ + R₂O)/(M₂O₃) 1.52 1.48 1.46 1.45 1.42 1.40 1.41 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.52 1.48 1.46 1.45 1.42 1.40 1.40 in mol % SiO₂ in wt % 50.5 48.5 46.6 51.9 49.9 48.0 48.0 Al₂O₃ in wt % 21.8 23.0 24.3 22.0 23.3 24.6 24.4 P₂O₅ in wt % 13.7 13.6 13.5 11.9 11.8 11.7 11.8 Na₂O in wt % 14.1 14.8 15.6 14.2 15.0 15.8 15.8 MgO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional none none none none none none XRF analysis Density (g/cm³) 2.388 2.401 2.412 2.393 2.406 2.416 2.416 Molar Volume 30.41 30.43 30.47 30.01 30.03 30.08 30.08 (cm³/mol) Strain Pt. (° C.) 615 620 625 633 638 640 640 Anneal Pt. (° C.) 675 678 682 693 697 699 699 Softening Pt. (° C.) 963 958 951 973 978 969 969 Temperature at 200 P 1732 1708 1683 1752 1720 1698 1698 Viscosity (° C.) Temperature at 35 kP 1284 1274 1260 1304 1289 1275 1275 Viscosity (° C.) Temperature at 160 1195 1186 1176 1215 1202 1191 1191 kP Viscosity (° C.) Liquidus 775 740 730 770 790 770 890 Temperature (° C.) Liquidus Viscosity 2.91E+10  8.74E+10  4.40E+11  1.67E+11  2.46E+10  2.04E+11 7.09E+08 (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 675 678 682 693 697 699 795 temperature (° C.) 410° C. 1 hr 777 820 881 819 878 938 804 Compressive Stress (MPa) 410° C. 1 hr Depth of 40 38 38 39 37 36 43 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr Compressive Stress (MPa) 410° C. 2 hr Depth of Layer (mm) 410° C. 2 hr Vickers Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr 718 760 818 758 819 over Compressive Stress (MPa) 410° C. 4 hr Depth of 80 82 80 77 77 over Layer (mm) 410° C. 4 hr Vickers >25 >20 >20 >15 >25 >15 Crack Initiation Load (kgf) 410° C. 8 hr 678 over over over over over Compressive Stress (MPa) 410° C. 8 hr Depth of 113 over over over over over Layer (mm) D FSM DOL 5.7E−10 5.1E−10 5.1E−10 5.4E−10 4.9E−10  4.6E−10  6.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL 5.7E−10 6.0E−10 5.7E−10 5.3E−10 5.3E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL 5.7E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 8 9 10 11 12 13 14 SiO₂ in mol % 60.0 60.0 60.0 60.0 60.0 60.0 62.0 Al₂O₃ in mol % 16.0 16.0 16.0 16.0 16.0 16.0 15.0 P₂O₅ in mol % 5.0 5.0 6.0 6.0 7.0 7.0 5.0 Na₂O in mol % 16.0 16.0 16.0 16.0 16.0 16.0 15.0 MgO in mol % 3.0 0.0 2.0 0.0 1.0 0.0 3.0 ZnO in mol % 0.0 3.0 0.0 2.0 0.0 1.0 0.0 SnO₂ in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 CaO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.84 0.84 0.89 0.89 0.94 0.94 0.83 (P₂O₅ + R₂O)/(M₂O₃) 1.31 1.31 1.38 1.38 1.44 1.44 1.33 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.50 1.50 1.50 1.50 1.50 1.50 1.53 in mol % SiO₂ in wt % 51.1 50.2 50.3 49.8 49.6 49.4 53.1 Al₂O₃ in wt % 23.1 22.7 22.8 22.5 22.5 22.3 21.8 P₂O₅ in wt % 10.1 9.9 11.9 11.8 13.7 13.6 10.1 Na₂O in wt % 14.0 13.8 13.8 13.7 13.7 13.6 13.3 MgO in wt % 1.7 0.0 1.1 0.0 0.6 0.0 1.7 ZnO in wt % 0.0 3.4 0.0 2.2 0.0 1.1 0.0 SnO₂ in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional none none none none none none none analysis Density (g/cm³) 2.417 2.453 2.406 2.428 2.393 2.404 2.423 Molar Volume 29.21 29.28 29.76 29.83 30.35 30.38 28.95 (cm³/mol) Strain Pt. (° C.) 643 621 623 619 611 621 680 Anneal Pt. (° C.) 696 681 684 681 675 683 730 Softening Pt. (° C.) 964 954.3 963.5 963.4 965 967.4 989.1 Temperature at 200 P 1668 1677 1695 1698 1714 1713 1676 Viscosity (° C.) Temperature at 35 kP 1247 1252 1268 1265 1280 1277 1252 Viscosity (° C.) Temperature at 160 1162 1166 1181 1178 1193 1190 1167 kP Viscosity (° C.) Liquidus 960 1100 Temperature (° C.) Liquidus Viscosity 1.85E+07  6.28E+05  (P) Zircon Breakdown 1240 >1265 Temperature (° C.) Zircon Breakdown 39255 <28281 Viscosity (P) Stress Optical 3.015 3.132 3.055 3.122 2.999 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 798 754 767 745 778 778 824 temperature (° C.) 410° C. 1 hr 932 963 833 895 817 820 970 Compressive Stress (MPa) 410° C. 1 hr Depth of 32 28 33 32 39 39 33 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 901 959 813 874 797 796 959 Compressive Stress (MPa) 410° C. 2 hr Depth of 44 38 48 46 54 53 44 Layer (mm) 410° C. 2 hr Vickers >30 >20 >20 >20 >20 >20 >20 Crack Initiation Load (kgf) 410° C. 3 hr 895 949 808 868 787 781 Compressive Stress (MPa) 410° C. 3 hr Depth of 54 46 57 55 65 65 Layer (mm) 410° C. 4 hr 884 942 792 842 770 772 Compressive Stress (MPa) 410° C. 4 hr Depth of 63 54 64 63 76 76 Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 3.6E−10 2.8E−10 3.9E−10 3.6E−10 5.4E−10 5.4E−10 3.9E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 3.4E−10 2.6E−10 4.1E−10 3.7E−10 5.2E−10 5.0E−10 3.4E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL 3.4E−10 2.5E−10 3.8E−10 3.6E−10 5.0E−10 5.0E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL 3.5E−10 2.6E−10 3.6E−10 3.5E−10 5.1E−10 5.1E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 15 16 17 18 19 20 21 SiO₂ in mol % 61.0 63.1 61.2 61.3 60.8 60.9 60.3 Al₂O₃ in mol % 14.8 13.9 15.9 15.8 16.0 15.8 15.7 P₂O₅ in mol % 4.9 5.0 5.0 4.9 4.9 4.9 5.5 Na₂O in mol % 15.3 13.9 15.8 16.0 16.1 15.8 16.0 MgO in mol % 3.8 4.1 2.0 2.0 2.0 2.5 2.5 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.0 0.0 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.1 0.0 0.0 0.0 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.77 0.77 0.90 0.88 0.88 0.86 0.85 (P₂O₅ + R₂O)/(M₂O₃) 1.36 1.36 1.30 1.32 1.31 1.31 1.37 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.63 1.65 1.43 1.45 1.44 1.47 1.53 in mol % SiO₂ in wt % 52.5 54.6 52.0 52.1 51.7 51.9 51.0 Al₂O₃ in wt % 21.6 20.4 23.0 22.7 23.1 22.8 22.5 P₂O₅ in wt % 10.0 10.2 10.0 9.8 9.8 9.8 10.9 Na₂O in wt % 13.6 12.4 13.8 14.0 14.1 13.9 13.9 MgO in wt % 2.2 2.4 1.1 1.1 1.1 1.4 1.4 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.0 0.0 0.1 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.411 2.404 2.413 2.415 2.417 2.418 2.416 Molar Volume 28.98 28.89 29.32 29.26 29.28 29.17 29.38 (cm³/mol) Strain Pt. (° C.) 659 672 631 630 628 630 631 Anneal Pt. (° C.) 709 734 689 687 685 683 685 Softening Pt. (° C.) 980.3 999.4 977.9 973.6 969.2 968.2 960.6 Temperature at 200 P 1695 1711 1704 1699 1698 1691 1687 Viscosity (° C.) Temperature at 35 kP 1260 1270 1285 1273 1274 1268 1263 Viscosity (° C.) Temperature at 160 1173 1183 1197 1187 1188 1182 1177 kP Viscosity (° C.) Liquidus 970 Temperature (° C.) Liquidus Viscosity 2.97E+07  (P) Zircon Breakdown >1260 Temperature (° C.) Zircon Breakdown <52623 Viscosity (P) Stress Optical 3.095 3.014 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 797 831 787 784 781 775 782 temperature (° C.) 410° C. 1 hr 919 875 918 966 954 Compressive Stress (MPa) 410° C. 1 hr Depth of 36 32 37 35 35 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 917 863 879 906 926 942 912 Compressive Stress (MPa) 410° C. 2 hr Depth of 48 45 47 49 46 48 47 Layer (mm) 410° C. 2 hr Vickers >20 15-20 >20 15-20 15-20 15-20 15-20 Crack Initiation Load (kgf) 410° C. 3 hr 881 855 856 906 924 910 878 Compressive Stress (MPa) 410° C. 3 hr Depth of 56 56 57 59 55 56 55 Layer (mm) 410° C. 4 hr 874 854 858 869 898 896 Compressive Stress (MPa) 410° C. 4 hr Depth of 65 65 66 67 64 65 Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 4.6E−10 3.6E−10 4.9E−10 4.3E−10 4.3E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 4.1E−10 3.6E−10 3.9E−10 4.3E−10 3.7E−10 4.1E−10 3.9E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL 3.7E−10 3.7E−10 3.8E−10 4.1E−10 3.6E−10 3.7E−10 3.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL 3.7E−10 3.7E−10 4.0E−10 3.6E−10 3.7E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 22 23 24 25 26 27 28 SiO₂ in mol % 60.3 62.3 61.3 60.8 60.5 62.2 62.1 Al₂O₃ in mol % 15.9 14.7 15.7 16.0 15.9 14.6 14.6 P₂O₅ in mol % 5.5 4.9 5.0 5.0 5.2 5.0 5.0 Na₂O in mol % 16.2 15.0 16.0 16.1 16.3 15.1 15.2 MgO in mol % 1.9 2.0 1.9 2.0 2.0 3.1 0.1 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 3.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 1.0 0.0 0.0 0.0 0.1 0.0 (M₂O₃)/R_(x)O in mol % 0.88 0.82 0.87 0.88 0.87 0.80 0.80 (P₂O₅ + R₂O)/(M₂O₃) 1.36 1.36 1.34 1.32 1.35 1.37 1.38 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.48 1.56 1.46 1.45 1.47 1.59 1.59 in mol % SiO₂ in wt % 50.9 53.3 52.1 51.6 51.2 53.4 52.4 Al₂O₃ in wt % 22.8 21.3 22.6 23.0 22.9 21.2 20.9 P₂O₅ in wt % 10.9 10.0 10.0 10.0 10.4 10.1 9.9 Na₂O in wt % 14.1 13.2 14.0 14.1 14.2 13.3 13.2 MgO in wt % 1.1 1.1 1.1 1.1 1.1 1.8 0.0 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 3.4 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.8 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.415 2.415 2.414 2.417 2.416 2.413 2.449 Molar Volume 29.49 29.07 29.30 29.31 29.40 29.02 29.10 (cm³/mol) Strain Pt. (° C.) 632 644 638 639 636 652 614 Anneal Pt. (° C.) 688 695 694 696 694 702 671 Softening Pt. (° C.) 965.7 980.7 975.7 972.1 970.6 977.2 950 Temperature at 200 P 1690 1699 1703 1698 1691 1704 1702 Viscosity (° C.) Temperature at 35 kP 1267 1267 1278 1275 1269 1263 1253 Viscosity (° C.) Temperature at 160 1181 1179 1191 1189 1183 1178 1167 kP Viscosity (° C.) Liquidus Temperature (° C.) Liquidus Viscosity (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical 3.058 3.045 3.029 3.045 3.041 3.044 3.156 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 773 795 780 782 769 796 762 temperature (° C.) 410° C. 1 hr 873 901 Compressive Stress (MPa) 410° C. 1 hr Depth of 33 29 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 900 858 902 906 909 870 862 Compressive Stress (MPa) 410° C. 2 hr Depth of 47 47 47 47 46 47 41 Layer (mm) 410° C. 2 hr Vickers >20 15-20 15-20 15-20 >20 >20 15-20 Crack Initiation Load (kgf) 410° C. 3 hr 896 846 890 906 900 862 880 Compressive Stress (MPa) 410° C. 3 hr Depth of 55 56 56 55 53 55 49 Layer (mm) 410° C. 4 hr 864 870 Compressive Stress (MPa) 410° C. 4 hr Depth of 61 54 Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 3.9E−10 3.0E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 3.9E−10 3.9E−10 3.9E−10 3.9E−10 3.7E−10 3.9E−10 3.0E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL 3.6E−10 3.7E−10 3.7E−10 3.6E−10 3.3E−10 3.6E−10 2.8E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL 3.3E−10 2.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 29 30 31 32 33 34 35 SiO₂ in mol % 62.2 60.3 60.0 60.0 59.9 60.7 60.3 Al₂O₃ in mol % 14.8 15.6 15.6 15.8 15.7 15.4 15.5 P₂O₅ in mol % 5.0 5.0 5.0 5.0 5.0 4.9 5.4 Na₂O in mol % 15.3 15.9 16.2 16.4 16.3 15.9 15.8 MgO in mol % 2.5 3.0 0.0 2.6 2.9 2.9 3.0 ZnO in mol % 0.0 0.0 3.1 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.1 0.0 0.0 0.1 0.1 0.1 (M₂O₃)/R_(x)O in mol % 0.83 0.82 0.81 0.83 0.82 0.82 0.82 (P₂O₅ + R₂O)/(M₂O₃) 1.37 1.34 1.36 1.35 1.35 1.35 1.37 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.54 1.54 1.56 1.52 1.54 1.54 1.56 in mol % SiO₂ in wt % 53.2 51.4 50.3 51.0 51.0 51.8 51.2 Al₂O₃ in wt % 21.5 22.5 22.1 22.8 22.7 22.4 22.3 P₂O₅ in wt % 10.0 10.1 9.8 10.0 10.1 10.0 10.8 Na₂O in wt % 13.5 14.0 14.0 14.4 14.3 14.0 13.8 MgO in wt % 1.5 1.7 0.0 1.5 1.7 1.7 1.7 ZnO in wt % 0.0 0.0 3.5 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.411 2.424 2.46 2.423 2.426 2.422 2.422 Molar Volume 29.12 29.07 29.15 29.17 29.08 29.06 29.20 (cm³/mol) Strain Pt. (° C.) 642 646 618 641 633 630 625 Anneal Pt. (° C.) 696 696 674 693 682 681 676 Softening Pt. (° C.) 972.7 960.3 941.8 960 952.8 957.2 950.7 Temperature at 200 P 1713 1664 1668 1676 1670 1673 1672 Viscosity (° C.) Temperature at 35 kP 1271 1240 1238 1246 1243 1250 1241 Viscosity (° C.) Temperature at 160 1185 1155 1153 1162 1160 1164 1157 kP Viscosity (° C.) Liquidus 995 975 Temperature (° C.) Liquidus Viscosity 6.97E+06  1.21E+07  (P) Zircon Breakdown 1240 1265 Temperature (° C.) Zircon Breakdown 41251 23823 Viscosity (P) Stress Optical 3.05 2.938 3.112 3.009 2.994 3.018 3.266?? Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 795 794 749 791 779 775 772 temperature (° C.) 410° C. 1 hr 921 927 Compressive Stress (MPa) 410° C. 1 hr Depth of 28 33 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 868 943 921 946 948 890 834 Compressive Stress (MPa) 410° C. 2 hr Depth of 48 46 41 48 46 44 48 Layer (mm) 410° C. 2 hr Vickers >20 >20 15-20 10-15 10-15 >20 >20 Crack Initiation Load (kgf) 410° C. 3 hr 862 941 895 921 936 885 818 Compressive Stress (MPa) 410° C. 3 hr Depth of 55 54 47 55 51 55 52 Layer (mm) 410° C. 4 hr 894 924 875 Compressive Stress (MPa) 410° C. 4 hr Depth of 52 61 63 Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 2.8E−10 3.9E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 4.1E−10 3.7E−10 3.0E−10 4.1E−10 3.7E−10 3.4E−10 4.1E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL 3.6E−10 3.4E−10 2.6E−10 3.6E−10 3.1E−10 3.6E−10 3.2E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL 2.4E−10 3.3E−10 3.5E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 36 37 38 39 40 41 42 SiO₂ in mol % 60.0 60.4 60.2 62.8 61.3 61.1 60.9 Al₂O₃ in mol % 15.6 15.6 15.5 14.4 15.1 15.2 15.3 P₂O₅ in mol % 5.5 5.0 4.9 4.1 4.7 4.8 4.9 Na₂O in mol % 16.3 16.4 16.4 15.6 15.7 15.8 15.8 MgO in mol % 2.5 2.5 2.9 3.0 3.0 3.0 3.0 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.0 0.1 0.0 0.0 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.83 0.83 0.80 0.77 0.81 0.81 0.81 (P₂O₅ + R₂O)/(M₂O₃) 1.39 1.37 1.38 1.37 1.35 1.35 1.35 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.55 1.53 1.57 1.58 1.55 1.55 1.55 in mol % SiO₂ in wt % 50.8 51.4 51.4 54.5 52.6 52.3 52.1 Al₂O₃ in wt % 22.4 22.5 22.4 21.1 22.0 22.1 22.2 P₂O₅ in wt % 10.9 10.1 9.9 8.3 9.5 9.7 9.9 Na₂O in wt % 14.2 14.4 14.4 14.0 13.9 13.9 13.9 MgO in wt % 1.4 1.4 1.7 1.7 1.7 1.7 1.7 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.3 0.3 0.3 0.3 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.419 2.421 2.427 2.422 2.422 2.422 2.422 Molar Volume 29.35 29.17 29.00 28.58 28.92 28.98 29.03 (cm³/mol) Strain Pt. (° C.) 619 624 632 653 635 634 632 Anneal Pt. (° C.) 672 677 680 704 685 684 682 Softening Pt. (° C.) 954.2 956.8 952.6 977.4 963.1 961.8 957.4 Temperature at 200 P 1675 1680 1659 1709 1693 1690 1689 Viscosity (° C.) Temperature at 35 kP 1246 1255 1229 1263 1257 1256 1254 Viscosity (° C.) Temperature at 160 1161 1169 1145 1176 1170 1170 1168 kP Viscosity (° C.) Liquidus 985 990 Temperature (° C.) Liquidus Viscosity 1.00E+07  9.03E+06  (P) Zircon Breakdown 1260 1240 Temperature (° C.) Zircon Breakdown 27805 45159 Viscosity (P) Stress Optical 2.986 3.005 3.008 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 767 768 778 793 773 772 770 temperature (° C.) 410° C. 1 hr 925 979 973 967 967 Compressive Stress (MPa) 410° C. 1 hr Depth of 34 30 30 29 29 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 903 928 934 980 978 975 948 Compressive Stress (MPa) 410° C. 2 hr Depth of 46 46 46 42 41 41 41 Layer (mm) 410° C. 2 hr Vickers 15-20 10-15 15-20 15-20 15-20 15-20 10-15 Crack Initiation Load (kgf) 410° C. 3 hr 923 943 930 934 927 925 Compressive Stress (MPa) 410° C. 3 hr Depth of 54 53 53 51 51 51 Layer (mm) 410° C. 4 hr 920 949 948 943 941 Compressive Stress (MPa) 410° C. 4 hr Depth of 59 59 57 57 57 Layer (mm) 410° C. 4 hr Vickers 15-20 15-20 15-20 10-15 Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 4.1E−10 3.2E−10 3.2E−10 3.0E−10 3.0E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 3.7E−10 3.7E−10 3.7E−10 3.1E−10 3.0E−10 3.0E−10 3.0E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL 3.4E−10 3.3E−10 3.3E−10 3.1E−10 3.1E−10 3.1E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL 3.1E−10 3.1E−10 2.9E−10 2.9E−10 2.9E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr Example Number 43 44 45 46 47 48 49 SiO₂ in mol % 60.4 60.2 60.1 60.0 59.9 60.1 59.3 Al₂O₃ in mol % 15.5 15.6 15.6 15.6 15.7 15.6 15.3 P₂O₅ in mol % 5.0 5.0 5.1 5.1 5.1 5.2 5.7 Na₂O in mol % 15.9 16.0 16.0 16.0 16.1 16.1 16.5 MgO in mol % 3.0 3.0 3.0 3.0 3.0 2.9 2.9 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.82 0.82 0.82 0.82 0.82 0.82 0.79 (P₂O₅ + R₂O)/(M₂O₃) 1.35 1.35 1.35 1.35 1.35 1.37 1.46 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.54 1.55 1.55 1.54 1.54 1.55 1.65 in mol % SiO₂ in wt % 51.5 51.3 51.2 51.1 51.0 51.2 50.2 Al₂O₃ in wt % 22.4 22.5 22.6 22.6 22.7 22.5 22.0 P₂O₅ in wt % 10.1 10.2 10.2 10.2 10.3 10.4 11.4 Na₂O in wt % 14.0 14.0 14.0 14.1 14.1 14.1 14.5 MgO in wt % 1.7 1.7 1.7 1.7 1.7 1.6 1.7 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.3 0.3 0.3 0.3 0.3 0.3 0.3 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.423 2.424 2.425 2.424 2.424 2.423 2.424 Molar Volume 29.09 29.10 29.10 29.11 29.14 29.14 29.27 (cm³/mol) Strain Pt. (° C.) 628 629 633 630 629 615 603 Anneal Pt. (° C.) 680 680 680 681 680 664 651 Softening Pt. (° C.) 954 952.8 956.5 953.3 953 944.5 929.6 Temperature at 200 P 1684 1678 1676 1681 1678 1681 1665 Viscosity (° C.) Temperature at 35 kP 1257 1245 1248 1249 1251 1242 1225 Viscosity (° C.) Temperature at 160 1171 1160 1163 1166 1158 1141 kP Viscosity (° C.) Liquidus Temperature (° C.) Liquidus Viscosity (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 770 769 765 770 769 752 737 temperature (° C.) 410° C. 1 hr 975 964 992 Compressive Stress (MPa) 410° C. 1 hr Depth of 29 29 27 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 960 955 990 945 948 939 905 Compressive Stress (MPa) 410° C. 2 hr Depth of 41 40 38 38 38 38 39 Layer (mm) 410° C. 2 hr Vickers 25-30 25-30 >20 >20 >20 15-20 10-15 Crack Initiation Load (kgf) 410° C. 3 hr 930 933 970 Compressive Stress (MPa) 410° C. 3 hr Depth of 50 50 53 Layer (mm) 410° C. 4 hr 948 940 Compressive Stress (MPa) 410° C. 4 hr Depth of 56 56 Layer (mm) 410° C. 4 hr Vickers 25-30 20-25 Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 3.0E−10 3.0E−10 2.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 3.0E−10 2.8E−10 2.6E−10 2.6E−10 2.6E−10 2.6E−10 2.7E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL 3.0E−10 3.0E−10 3.3E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL 2.8E−10 2.8E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 50 51 52 53 54 55 56 SiO₂ in mol % 61.8 56.9 60.1 60.2 60.1 61.1 61.0 Al₂O₃ in mol % 13.5 13.4 15.0 15.4 15.2 14.6 14.9 P₂O₅ in mol % 5.0 10.0 6.0 5.4 5.7 5.4 5.5 Na₂O in mol % 19.5 19.6 15.7 15.9 15.9 15.2 15.5 MgO in mol % 0.0 0.0 3.0 3.0 3.0 3.5 3.1 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.0 0.1 0.1 0.1 0.1 0.1 (M₂O₃)/R_(x)O in mol % 0.69 0.68 0.80 0.81 0.80 0.78 0.80 (P₂O₅ + R₂O)/(M₂O₃) 1.82 2.21 1.44 1.38 1.42 1.41 1.41 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.82 2.21 1.64 1.58 1.62 1.65 1.62 in mol % SiO₂ in wt % 52.9 46.0 50.9 51.2 50.9 52.2 51.9 Al₂O₃ in wt % 19.5 18.4 21.6 22.2 21.9 21.2 21.5 P₂O₅ in wt % 10.1 19.1 11.9 10.7 11.3 10.9 11.0 Na₂O in wt % 17.2 16.3 13.7 13.9 13.9 13.4 13.6 MgO in wt % 0.0 0.0 1.7 1.7 1.7 2.0 1.7 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.426 2.408 2.413 2.419 2.416 2.415 2.415 Molar Volume 28.96 30.85 29.45 29.23 29.34 29.10 29.21 (cm³/mol) Strain Pt. (° C.) 574 522 626 637 630 649 639 Anneal Pt. (° C.) 625 568 679 688 681 701 689 Softening Pt. (° C.) 872.9 825.1 947.3 955.1 949.9 969.4 961 Temperature at 200 P 1651 1587 1686 1679 1684 1678 1698 Viscosity (° C.) Temperature at 35 kP 1162 1126 1248 1253 1248 1248 1256 Viscosity (° C.) Temperature at 160 1075 1040 1162 1169 1163 1163 1172 kP Viscosity (° C.) Liquidus 990 915 1000 Temperature (° C.) Liquidus Viscosity 9.59E+05  2.61E+06  6.34E+06  (P) Zircon Breakdown 1235 >1245.123 1275 >1270 >1300 Temperature (° C.) Zircon Breakdown 11856 <6194 22653 <26470 <15377 Viscosity (P) Stress Optical 3.069 3.107 2.986 3.089 3.064 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 710 650 769 776 769 790 777 temperature (° C.) 410° C. 1 hr 850 891 870 852 867 Compressive Stress (MPa) 410° C. 1 hr Depth of 47 37 38 37 38 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 501 496 857 873 848 841 829 Compressive Stress (MPa) 410° C. 2 hr Depth of 90 88 52 49 52 50 50 Layer (mm) 410° C. 2 hr Vickers >20 >20 20-30 >20 >20 >20 10-15 Crack Initiation Load (kgf) 410° C. 3 hr 842 863 834 836 832 Compressive Stress (MPa) 410° C. 3 hr Depth of 59 64 63 63 64 Layer (mm) 410° C. 4 hr 828 859 842 826 835 Compressive Stress (MPa) 410° C. 4 hr Depth of 70 72 70 73 72 Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 7.8E−10 4.9E−10 5.1E−10 4.9E−10 5.1E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 1.4E−09 1.4E−09 4.8E−10 4.3E−10 4.8E−10 4.4E−10 4.4E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL 4.1E−10 4.8E−10 4.7E−10 4.7E−10 4.8E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL 4.3E−10 4.6E−10 4.3E−10 4.7E−10 4.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 57 58 59 60 61 62 63 SiO₂ in mol % 60.2 60.2 60.3 60.4 60.3 60.4 60.2 Al₂O₃ in mol % 15.0 15.3 15.1 15.5 15.3 15.4 15.1 P₂O₅ in mol % 5.5 6.0 5.9 5.9 5.9 5.9 6.0 Na₂O in mol % 15.6 15.4 15.1 15.4 15.3 15.4 15.2 MgO in mol % 3.5 3.0 3.6 2.5 3.1 2.8 3.4 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.1 0.0 0.1 0.0 0.1 0.1 0.1 (M₂O₃)/R_(x)O in mol % 0.78 0.83 0.81 0.86 0.83 0.85 0.81 (P₂O₅ + R₂O)/(M₂O₃) 1.41 1.40 1.39 1.38 1.39 1.38 1.40 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.65 1.59 1.63 1.54 1.59 1.56 1.63 in mol % SiO₂ in wt % 51.3 50.9 51.1 50.9 51.0 50.9 50.9 Al₂O₃ in wt % 21.7 21.9 21.7 22.2 21.9 22.1 21.7 P₂O₅ in wt % 11.0 11.9 11.7 11.8 11.8 11.8 11.9 Na₂O in wt % 13.8 13.4 13.2 13.4 13.3 13.4 13.3 MgO in wt % 2.0 1.7 2.0 1.4 1.7 1.6 1.9 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.42 2.41 2.42 2.41 2.42 2.41 2.41 Molar Volume 29.13 29.49 29.32 29.57 29.43 29.50 29.41 (cm³/mol) Strain Pt. (° C.) 647 627 634 624 627 625 627 Anneal Pt. (° C.) 697 682 684 680 680 679 679 Softening Pt. (° C.) 962.8 952 959.1 954.6 951 951.6 954.9 Temperature at 200 P 1677 1728 1679 1693 1685 1687 1673 Viscosity (° C.) Temperature at 35 kP 1247 1257 1246 1259 1253 1257 1235 Viscosity (° C.) Temperature at 160 1163 1173 1160 1173 1168 1171 1151 kP Viscosity (° C.) Liquidus 1090 Temperature (° C.) Liquidus Viscosity 6.79E+05  (P) Zircon Breakdown 1265 >1250 Temperature (° C.) Zircon Breakdown 25644 <27583 Viscosity (P) Stress Optical 3.046 3.092 3.085 3.037 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 784 776 778 779 779 773 787 temperature (° C.) 410° C. 1 hr 883 Compressive Stress (MPa) 410° C. 1 hr Depth of 37 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 870 879 910 878 869 885 885 Compressive Stress (MPa) 410° C. 2 hr Depth of 52 46 45 47 50 46 45 Layer (mm) 410° C. 2 hr Vickers >20 30-40 30-40 30-40 20-30 20-30 30-40 Crack Initiation Load (kgf) 410° C. 3 hr 861 Compressive Stress (MPa) 410° C. 3 hr Depth of 63 Layer (mm) 410° C. 4 hr 853 Compressive Stress (MPa) 410° C. 4 hr Depth of 71 Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 4.9E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 4.8E−10 3.8E−10 3.6E−10 3.9E−10 4.4E−10 3.7E−10 3.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL 4.7E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL 4.5E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 64 65 66 67 68 69 70 SiO₂ in mol % 59.9 60.0 60.1 60.1 60.2 60.2 57.1 Al₂O₃ in mol % 15.5 15.3 15.5 15.2 15.4 15.0 17.5 P₂O₅ in mol % 5.4 5.3 3.6 5.6 5.8 5.8 6.8 Na₂O in mol % 15.9 15.6 15.5 15.4 15.4 15.2 18.4 MgO in mol % 3.1 3.6 3.1 3.6 3.0 3.6 0.1 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.81 0.80 0.83 0.80 0.83 0.80 0.95 (P₂O₅ + R₂O)/(M₂O₃) 1.38 1.37 1.24 1.38 1.39 1.40 1.44 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.58 1.60 1.44 1.61 1.58 1.63 1.45 in mol % SiO₂ in wt % 50.9 51.2 53.1 51.1 50.9 51.2 46.8 Al₂O₃ in wt % 22.3 22.1 23.1 21.9 22.0 21.7 24.2 P₂O₅ in wt % 10.8 10.7 7.6 11.2 11.7 11.6 13.2 Na₂O in wt % 14.0 13.7 14.1 13.5 13.5 13.3 15.5 MgO in wt % 1.8 2.1 1.8 2.0 1.7 2.0 0.0 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.419 2.421 2.417 2.419 2.415 2.416 2.41 Molar Volume 29.23 29.12 28.17 29.23 29.43 29.29 30.41 (cm³/mol) Strain Pt. (° C.) 637 640 631 638 629 634 619 Anneal Pt. (° C.) 689 689 683 687 681 684 679 Softening Pt. (° C.) 958 962.4 956.3 962.4 954.1 959.7 953.7 Temperature at 200 P 1680 1670 1675 1665 1681 1676 1680 Viscosity (° C.) Temperature at 35 kP 1253 1249 1245 1240 1253 1247 1246 Viscosity (° C.) Temperature at 160 1168 1165 1159 1155 1167 1162 1165 kP Viscosity (° C.) Liquidus 855 Temperature (° C.) Liquidus Viscosity 1.99E+09  (P) Zircon Breakdown 1225 Temperature (° C.) Zircon Breakdown 50768 Viscosity (P) Stress Optical 2.997 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 778 776 773 774 771 772 776 temperature (° C.) 410° C. 1 hr 808 Compressive Stress (MPa) 410° C. 1 hr Depth of 43 Layer (mm) 410° C. 1 hr Vickers >50 Crack Initiation Load (kgf) 410° C. 2 hr 929 925 914 914 898 900 Compressive Stress (MPa) 410° C. 2 hr Depth of 48 47 49 48 50 48 Layer (mm) 410° C. 2 hr Vickers >20 >20 >20 >20 >20 >20 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 6.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 4.1E−10 3.9E−10 4.3E−10 4.1E−10 4.4E−10 4.1E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 71 72 73 74 75 76 77 SiO₂ in mol % 56.4 55.5 56.2 56.3 57.4 57.3 56.4 Al₂O₃ in mol % 17.4 17.4 16.5 14.5 16.6 14.5 16.5 P₂O₅ in mol % 8.0 8.9 8.0 7.9 7.0 6.9 7.9 Na₂O in mol % 18.1 18.0 18.1 18.0 17.8 18.1 19.0 MgO in mol % 0.1 0.1 1.0 3.1 1.0 3.0 0.0 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.96 0.97 0.86 0.69 0.88 0.69 0.87 (P₂O₅ + R₂O)/(M₂O₃) 1.50 1.54 1.59 1.79 1.50 1.72 1.62 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.50 1.55 1.65 2.00 1.56 1.93 1.62 in mol % SiO₂ in wt % 45.6 44.4 45.8 46.7 47.3 48.0 45.9 Al₂O₃ in wt % 23.9 23.7 22.8 20.4 23.2 20.6 22.8 P₂O₅ in wt % 15.2 16.8 15.4 15.5 13.6 13.8 15.1 Na₂O in wt % 15.1 14.9 15.2 15.4 15.2 15.6 16.0 MgO in wt % 0.0 0.0 0.6 1.7 0.5 1.7 0.0 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.41 2.41 2.42 2.43 2.42 2.43 2.42 Molar Volume 30.82 31.19 30.54 29.86 30.16 29.49 30.58 (cm³/mol) Strain Pt. (° C.) 603 591 586 571 601 588 586 Anneal Pt. (° C.) 661 648 642 619 658 634 642 Softening Pt. (° C.) 932.5 916.5 909.5 877.4 928.3 900.7 906.5 Temperature at 200 P 1653 1660 1641 1603 1660 1616 1644 Viscosity (° C.) Temperature at 35 kP 1227 1224 1214 1171 1233 1183 1212 Viscosity (° C.) Temperature at 160 1142 1138 1128 1086 1148 1098 1126 kP Viscosity (° C.) Liquidus 800 Temperature (° C.) Liquidus Viscosity 2.74E+09  (P) Zircon Breakdown 1265 Temperature (° C.) Zircon Breakdown 18914 Viscosity (P) Stress Optical 3.038 3.005 2.998 2.992 2.977 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 756 742 735 703 752 717 734 temperature (° C.) 410° C. 1 hr 888 734 816 809 Compressive Stress (MPa) 410° C. 1 hr Depth of 43 44 49 45 Layer (mm) 410° C. 1 hr Vickers 40-50 Crack Initiation Load (kgf) 410° C. 2 hr 731 706 706 804 775 711 Compressive Stress (MPa) 410° C. 2 hr Depth of 62 62 60 58 59 68 Layer (mm) 410° C. 2 hr Vickers >40 >40 >20 30-40 >20 >20 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 6.6E−10 6.9E−10 8.5E−10 7.2E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 6.9E−10 6.8E−10 6.4E−10 5.9E−10 6.2E−10 8.3E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 78 79 80 81 82 83 84 SiO₂ in mol % 56.3 57.2 57.6 50.4 56.4 55.9 55.4 Al₂O₃ in mol % 15.5 16.5 15.5 19.8 18.1 18.1 18.1 P₂O₅ in mol % 7.9 6.9 6.8 9.8 7.2 7.7 7.7 Na₂O in mol % 20.0 19.1 20.0 19.9 18.2 18.2 18.1 MgO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.6 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.78 0.86 0.78 0.99 0.99 0.99 0.96 (P₂O₅ + R₂O)/(M₂O₃) 1.80 1.58 1.73 1.50 1.41 1.43 1.43 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.80 1.58 1.73 1.50 1.41 1.43 1.46 in mol % SiO₂ in wt % 46.1 47.0 47.7 39.4 45.8 45.2 44.9 Al₂O₃ in wt % 21.5 23.0 21.7 26.3 24.9 24.8 24.8 P₂O₅ in wt % 15.3 13.5 13.3 18.1 13.9 14.7 14.7 Na₂O in wt % 16.9 16.2 17.0 16.0 15.2 15.1 15.1 MgO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.3 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.42 2.42 2.43 2.42 2.41 2.41 2.42 Molar Volume 30.36 30.22 29.94 31.72 30.65 30.81 30.74 (cm³/mol) Strain Pt. (° C.) 572 601 582 588 617 610 607 Anneal Pt. (° C.) 624 658 634 644 676 670 664 Softening Pt. (° C.) 879.4 924.2 888.5 904 951.4 947.1 939.1 Temperature at 200 P 1623 1659 1634 1603 1672 1660 1664 Viscosity (° C.) Temperature at 35 kP 1180 1224 1190 1192 1254 1250 1233 Viscosity (° C.) Temperature at 160 1093 1138 1104 1111 1170 1166 1152 kP Viscosity (° C.) Liquidus 865 800 Temperature (° C.) Liquidus Viscosity 5.74E+08  5.51E+09  (P) Zircon Breakdown 1215 1245 Temperature (° C.) Zircon Breakdown 69204 38105 Viscosity (P) Stress Optical 2.97 2.935 2.999 3.051 3.028 3.044 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 692 751 699 716 750 750 740 temperature (° C.) 410° C. 1 hr 694 750 796 909 887 843 Compressive Stress (MPa) 410° C. 1 hr Depth of 64 60 46 41 42 41 Layer (mm) 410° C. 1 hr Vickers 30-40 >50 >50 Crack Initiation Load (kgf) 410° C. 2 hr 680 751 732 749 837 Compressive Stress (MPa) 410° C. 2 hr Depth of 81 66 75 63 56 Layer (mm) 410° C. 2 hr Vickers >20 >20 >30 30-40 >40 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 1.5E−09 1.3E−09 7.5E−10 6.0E−10 6.3E−10 6.0E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 1.2E−09 7.8E−10 1.0E−09 7.0E−10 5.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 85 86 87 88 89 90 91 SiO₂ in mol % 58.3 58.3 58.6 58.3 58.4 58.4 59.2 Al₂O₃ in mol % 15.8 15.6 15.4 15.6 15.4 15.1 15.3 P₂O₅ in mol % 6.8 6.7 6.7 6.8 6.7 6.7 6.8 Na₂O in mol % 15.9 15.7 15.2 15.6 15.4 15.1 15.5 MgO in mol % 3.1 3.0 3.1 3.5 3.5 3.5 3.1 ZnO in mol % 0.0 0.5 0.9 0.0 0.5 1.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 (M₂O₃)/R_(x)O in mol % 0.83 0.81 0.80 0.81 0.79 0.77 0.82 (P₂O₅ + R₂O)/(M₂O₃) 1.43 1.43 1.42 1.44 1.44 1.45 1.45 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.63 1.66 1.68 1.67 1.70 1.75 1.66 in mol % SiO₂ in wt % 48.6 48.6 48.9 48.8 48.8 48.9 49.5 Al₂O₃ in wt % 22.4 22.1 21.9 22.1 21.8 21.5 21.7 P₂O₅ in wt % 13.4 13.2 13.1 13.4 13.3 13.3 13.4 Na₂O in wt % 13.6 13.5 13.1 13.5 13.3 13.1 13.4 MgO in wt % 1.7 1.7 1.7 2.0 2.0 2.0 1.7 ZnO in wt % 0.0 0.5 1.0 0.0 0.5 1.1 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.42 2.42 2.43 2.42 2.42 2.43 2.41 Molar Volume 29.81 29.70 29.62 29.72 29.63 29.52 29.78 (cm³/mol) Strain Pt. (° C.) 612 614 611 615 614 616 612 Anneal Pt. (° C.) 664 666 661 666 663 664 666 Softening Pt. (° C.) 932.6 935.5 928.4 934 932.5 932.8 942.5 Temperature at 200 P 1660 1656 1654 1655 1651 1650 1675 Viscosity (° C.) Temperature at 35 kP 1235 1231 1226 1232 1227 1220 1244 Viscosity (° C.) Temperature at 160 1150 1147 1141 1147 1143 1136 1158 kP Viscosity (° C.) Liquidus 975 Temperature (° C.) Liquidus Viscosity 1.07E+07 (P) Zircon Breakdown >1300 Temperature (° C.) Zircon Breakdown <14599 Viscosity (P) Stress Optical 3.109 3.112 3.069 3.049 3.082 3.021 3.03 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 753 755 748 754 749 749 758 temperature (° C.) 410° C. 1 hr 873 Compressive Stress (MPa) 410° C. 1 hr Depth of 33 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 861 862 861 850 881 874 853 Compressive Stress (MPa) 410° C. 2 hr Depth of 49 47 46 47 46 45 45 Layer (mm) 410° C. 2 hr Vickers >40 >40 >40 >40 >40 >40 >50 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 3.9E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 4.3E−10 3.9E−10 3.7E−10 3.9E−10 3.7E−10 3.6E−10 3.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 92 93 94 95 96 97 98 SiO₂ in mol % 59.2 59.3 59.3 59.3 59.2 59.3 58.4 Al₂O₃ in mol % 15.0 14.8 15.1 14.8 14.6 15.1 16.0 P₂O₅ in mol % 6.8 6.8 6.8 6.8 6.8 6.7 6.8 Na₂O in mol % 15.2 14.9 15.1 14.9 14.8 15.2 15.9 MgO in mol % 3.1 3.0 3.5 3.6 3.6 3.6 2.7 ZnO in mol % 0.5 1.0 0.0 0.5 1.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.1 0.1 0.1 0.1 0.1 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.80 0.78 0.81 0.78 0.75 0.80 0.86 (P₂O₅ + R₂O)/(M₂O₃) 1.46 1.47 1.45 1.46 1.48 1.45 1.41 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.71 1.74 1.69 1.74 1.80 1.69 1.58 in mol % SiO₂ in wt % 49.6 49.6 49.7 49.8 49.7 49.9 48.7 Al₂O₃ in wt % 21.3 21.0 21.5 21.1 20.7 21.5 22.7 P₂O₅ in wt % 13.4 13.4 13.5 13.4 13.4 13.3 13.3 Na₂O in wt % 13.2 12.9 13.1 12.9 12.8 13.2 13.7 MgO in wt % 1.7 1.7 2.0 2.0 2.0 2.0 1.5 ZnO in wt % 0.6 1.1 0.0 0.6 1.1 0.0 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.2 0.1 0.1 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.43 2.41 2.41 2.42 2.43 2.411 2.414 Molar Volume 29.61 29.79 29.71 29.59 29.48 29.64 29.87 (cm³/mol) Strain Pt. (° C.) 615 613 617 620 620 616 612 Anneal Pt. (° C.) 669 663 668 671 669 669 666 Softening Pt. (° C.) 936.3 934.5 939.7 938.2 942.5 940.7 940.2 Temperature at 200 P 1667 1666 1663 1670 1657 1666 1661 Viscosity (° C.) Temperature at 35 kP 1241 1234 1233 1235 1216 1240 1243 Viscosity (° C.) Temperature at 160 1156 1148 1147 1151 1133 1153 1158 kP Viscosity (° C.) Liquidus Temperature (° C.) Liquidus Viscosity (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical 3.067 3.117 3.08 3.115 3.091 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 760 751 757 759 756 760 758 temperature (° C.) 410° C. 1 hr 864 896 Compressive Stress (MPa) 410° C. 1 hr Depth of 29 30 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 831 844 832 850 838 870 889 Compressive Stress (MPa) 410° C. 2 hr Depth of 46 44 45 47 44 43 42 Layer (mm) 410° C. 2 hr Vickers >40 >40 >40 >40 >40 40-50 >50 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 3.0E−10 3.2E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 3.7E−10 3.4E−10 3.6E−10 3.9E−10 3.4E−10 3.3E−10 3.1E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 99 100 101 102 103 104 105 SiO₂ in mol % 58.2 59.4 56.6 56.3 59.9 60.5 60.9 Al₂O₃ in mol % 15.6 16.0 16.0 16.1 15.1 15.1 15.0 P₂O₅ in mol % 6.8 6.8 7.6 7.7 6.8 6.8 6.8 Na₂O in mol % 15.8 16.0 15.9 16.2 15.1 15.0 15.1 MgO in mol % 3.6 1.7 3.7 3.6 3.1 2.6 2.1 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.80 0.90 0.82 0.81 0.83 0.86 0.88 (P₂O₅ + R₂O)/(M₂O₃) 1.45 1.43 1.47 1.48 1.45 1.44 1.46 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.68 1.53 1.70 1.71 1.66 1.61 1.59 in mol % SiO₂ in wt % 48.7 49.3 46.8 46.5 50.2 50.7 50.9 Al₂O₃ in wt % 22.1 22.6 22.5 22.6 21.4 21.4 21.3 P₂O₅ in wt % 13.4 13.3 14.9 15.0 13.5 13.4 13.5 Na₂O in wt % 13.6 13.8 13.6 13.8 13.0 13.0 13.0 MgO in wt % 2.0 1.0 2.1 2.0 1.7 1.4 1.2 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.415 2.406 2.417 2.417 2.405 2.4 2.396 Molar Volume 29.70 30.05 30.04 30.08 29.78 29.87 29.98 (cm³/mol) Strain Pt. (° C.) 612 613 596 598 607 607 613 Anneal Pt. (° C.) 664 671 649 652 663 663 671 Softening Pt. (° C.) 937.7 951.1 918.5 919.9 945.2 949.4 955.8 Temperature at 200 P 1658 1698 1631 1637 1682 1695 1709 Viscosity (° C.) Temperature at 35 kP 1235 1262 1215 1219 1251 1262 1271 Viscosity (° C.) Temperature at 160 1150 1176 1131 1135 1164 1174 1182 kP Viscosity (° C.) Liquidus Temperature (° C.) Liquidus Viscosity (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 754 767 739 743 758 759 768 temperature (° C.) 410° C. 1 hr 895 889 855 853 839 823 817 Compressive Stress (MPa) 410° C. 1 hr Depth of 29 32 28 28 30 31 31 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 890 843 865 856 846 820 803 Compressive Stress (MPa) 410° C. 2 hr Depth of 43 49 41 42 44 45 46 Layer (mm) 410° C. 2 hr Vickers >50 >50 >50 >50 40-50 40-50 40-50 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 3.0E−10 3.6E−10 2.8E−10 2.8E−10 3.2E−10 3.4E−10 3.4E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 3.3E−10 4.3E−10 3.0E−10 3.1E−10 3.4E−10 3.6E−10 3.7E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 106 107 108 109 110 111 112 113 SiO₂ in mol % 56.8 55.8 55.7 55.9 56.0 55.8 55.8 59.9 Al₂O₃ in mol % 17.9 18.0 18.0 18.0 18.0 18.0 18.0 15.7 P₂O₅ in mol % 7.2 7.8 7.8 7.7 7.7 7.7 7.8 5.4 Na₂O in mol % 17.9 16.1 16.3 16.6 16.6 17.0 17.0 16.2 MgO in mol % 0.1 2.0 0.1 1.5 0.1 1.3 0.1 2.6 ZnO in mol % 0.0 0.0 2.0 0.0 1.4 0.0 1.2 0.0 SnO₂ in mol % 0.0 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.1 0.0 0.1 0.0 0.0 0.0 0.1 (M₂O₃)/R_(x)O in 0.99 0.99 0.98 0.99 1.00 0.99 0.98 0.83 mol % (P₂O₅ + 1.40 1.33 1.34 1.35 1.35 1.37 1.38 1.38 R₂O)/(M₂O₃) in mol % (P₂O₅ + 1.41 1.44 1.45 1.44 1.43 1.44 1.45 1.55 R_(x)O)/(M₂O₃) in mol % SiO₂ in wt % 46.3 45.3 44.8 45.3 45.1 45.3 44.9 50.7 Al₂O₃ in wt % 24.7 24.9 24.6 24.8 24.6 24.8 24.6 22.5 P₂O₅ in wt % 13.9 14.9 14.7 14.8 14.6 14.8 14.8 10.9 Na₂O in wt % 15.0 13.5 13.5 13.9 13.8 14.2 14.1 14.2 MgO in wt % 0.0 1.1 0.0 0.8 0.0 0.7 0.0 1.5 ZnO in wt % 0.0 0.0 2.1 0.0 1.6 0.0 1.4 0.0 SnO₂ in wt % 0.0 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF XRF analysis Density 2.409 2.411 2.436 2.411 2.430 2.411 2.427 2.419 (g/cm³) Molar Volume 30.63 30.69 30.69 30.71 30.70 30.72 30.74 29.34 (cm³/mol) Strain Pt. (° C.) 617 621 609 618 604 617 613 629 Anneal Pt. 677 679 666 676 663 676 671 684 (° C.) Softening Pt. 956.5 950.7 935.8 949.4 939 949.5 941.5 953 (° C.) Temperature at 1673 1651 1650 1655 1659 1661 1681 1681 200 P Viscosity (° C.) Temperature at 1259 1247 1238 1247 1242 1250 1256 1256 35 kP Viscosity (° C.) Temperature at 1174 1164 1154 1164 1161 1167 1171 1171 160 kP Viscosity (° C.) Liquidus Temperature (° C.) Liquidus Viscosity (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical 3.088 3.118 3.127 3.183 3.036 3.124 3.147 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate 775 751 742 755 736 751 745 775 Fictive temperature (° C.) 410° C. 1 hr 869 916 912 921 899 922 969 Compressive Stress (MPa) 410° C. 1 hr 29 29 32 32 33 32 30 Depth of Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 854 884 895 892 901 868 889 933 Compressive Stress (MPa) 410° C. 2 hr 59 42 44 46 46 49 49 46 Depth of Layer (mm) 410° C. 2 hr >50 >50 >50 >50 >50 >50 >50 20-30 Vickers Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 3.0E−10 3.0E−10 3.6E−10 3.6E−10 3.9E−10 3.6E−10 3.2E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 6.2E−10 3.1E−10 3.4E−10 3.7E−10 3.7E−10 4.3E−10 4.3E−10 3.7E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 114 115 116 117 118 119 120 SiO₂ in mol % 59.2 58.4 57.9 57.1 56.5 56.8 57.4 Al₂O₃ in mol % 16.1 16.5 16.8 17.2 17.6 16.8 16.6 P₂O₅ in mol % 5.8 6.2 6.5 6.9 7.3 7.1 7.1 Na₂O in mol % 16.6 17.0 17.3 17.7 18.0 17.1 16.7 MgO in mol % 2.2 1.7 1.3 0.9 0.5 2.1 2.1 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.1 0.0 0.0 0.0 0.0 0.0 0.1 (M₂O₃)/R_(x)O in mol % 0.86 0.88 0.90 0.93 0.95 0.88 0.88 (P₂O₅ + R₂O)/(M₂O₃) 1.39 1.40 1.42 1.43 1.44 1.44 1.43 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.53 1.51 1.49 1.48 1.47 1.56 1.56 in mol % SiO₂ in wt % 49.7 48.7 47.9 46.9 46.0 46.8 47.4 Al₂O₃ in wt % 22.9 23.3 23.6 24.0 24.4 23.5 23.3 P₂O₅ in wt % 11.5 12.2 12.8 13.5 14.0 13.8 13.8 Na₂O in wt % 14.4 14.6 14.8 15.0 15.2 14.5 14.2 MgO in wt % 1.2 1.0 0.7 0.5 0.3 1.1 1.2 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.418 2.415 2.416 2.416 2.414 2.419 2.415 Molar Volume 29.58 29.86 30.07 30.30 30.54 30.14 30.14 (cm³/mol) Strain Pt. (° C.) 624 618 616 616 615 609 610 Anneal Pt. (° C.) 681 677 675 674 674 666 666 Softening Pt. (° C.) 954.9 950.5 948.1 947.9 949.3 930.8 940.6 Temperature at 200 P 1680 1673 1676 1670 1667 1654 1660 Viscosity (° C.) Temperature at 35 kP 1257 1253 1254 1250 1249 1235 1240 Viscosity (° C.) Temperature at 160 1171 1168 1169 1166 1164 1151 1156 kP Viscosity (° C.) Liquidus 955 Temperature (° C.) Liquidus Viscosity 2.67E+07  (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical 3.038 3.050 3.080 3.004 3.093 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 764 750 745 765 747 746 741 temperature (° C.) 410° C. 1 hr 942 953 918 899 888 921 900 Compressive Stress (MPa) 410° C. 1 hr Depth of 30 31 34 36 38 34 34 Layer (mm) 410° C. 1 hr Vickers >50 Crack Initiation Load (kgf) 410° C. 2 hr 945 924 901 868 853 913 895 Compressive Stress (MPa) 410° C. 2 hr Depth of 46 47 50 54 50 46 45 Layer (mm) 410° C. 2 hr Vickers 20-30 >50 >50 >40 >50 >50 30-40 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 3.2E−10 3.4E−10 4.1E−10 4.6E−10 5.1E−10 4.1E−10 4.1E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 3.7E−10 3.9E−10 4.4E−10 5.2E−10 4.4E−10 3.7E−10 3.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 121 122 123 124 125 126 127 SiO₂ in mol % 57.9 57.0 57.4 58.0 59.0 58.9 58.9 Al₂O₃ in mol % 16.4 16.7 16.6 16.2 15.5 15.7 16.0 P₂O₅ in mol % 7.1 7.3 7.3 7.4 6.4 6.5 6.4 Na₂O in mol % 16.5 16.7 16.5 16.3 15.4 15.7 16.0 MgO in mol % 2.1 2.0 2.0 2.0 3.5 3.0 2.5 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.1 0.1 0.0 0.1 0.1 0.1 0.1 (M₂O₃)/R_(x)O in mol % 0.88 0.89 0.89 0.88 0.82 0.84 0.86 (P₂O₅ + R₂O)/(M₂O₃) 1.44 1.43 1.44 1.46 1.41 1.41 1.40 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.56 1.56 1.57 1.59 1.64 1.60 1.56 in mol % SiO₂ in wt % 47.8 46.9 47.2 47.8 49.6 49.4 49.2 Al₂O₃ in wt % 23.0 23.4 23.1 22.6 22.1 22.4 22.7 P₂O₅ in wt % 13.8 14.2 14.3 14.4 12.8 12.8 12.7 Na₂O in wt % 14.0 14.2 14.0 13.8 13.4 13.6 13.8 MgO in wt % 1.1 1.1 1.1 1.1 2.0 1.7 1.4 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.2 0.2 0.2 0.2 0.1 0.1 0.1 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.411 2.415 2.412 2.409 2.415 2.414 2.413 Molar Volume 30.16 30.26 30.27 30.26 29.59 29.70 29.79 (cm³/mol) Strain Pt. (° C.) 609 607 607 605 617 612 613 Anneal Pt. (° C.) 667 663 663 662 669 666 669 Softening Pt. (° C.) 941.6 937.7 936.6 940.1 940.6 941.4 948.7 Temperature at 200 P 1670 1658 1661 1665 1666 1669 1677 Viscosity (° C.) Temperature at 35 kP 1247 1238 1241 1244 1241 1244 1250 Viscosity (° C.) Temperature at 160 1161 1154 1156 1159 1156 1159 1165 kP Viscosity (° C.) Liquidus Temperature (° C.) Liquidus Viscosity (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical 3.056 3.038 3.055 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 742 742 739 730 765 755 754 temperature (° C.) 410° C. 1 hr 885 889 876 857 Compressive Stress (MPa) 410° C. 1 hr Depth of 34 35 34 35 Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 874 870 861 838 907 889 896 Compressive Stress (MPa) 410° C. 2 hr Depth of 46 47 47 47 43 44 45 Layer (mm) 410° C. 2 hr Vickers >50 >50 >50 40-50 40-50 30-40 40-50 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL 4.1E−10 4.3E−10 4.1E−10 4.3E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 3.7E−10 3.9E−10 3.9E−10 3.9E−10 3.3E−10 3.4E−10 3.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 128 129 130 131 132 133 134 SiO₂ in mol % 58.2 57.8 57.9 56.8 56.9 56.9 56.8 Al₂O₃ in mol % 16.1 16.5 16.3 16.5 16.8 17.0 17.5 P₂O₅ in mol % 6.3 6.5 6.4 6.5 6.4 6.4 6.4 Na₂O in mol % 15.9 16.5 16.3 16.5 16.8 17.1 17.1 MgO in mol % 3.5 2.6 3.0 3.6 3.1 2.5 2.0 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.0 0.0 0.0 0.0 CaO in mol % 0.1 0.1 0.1 0.0 0.0 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.83 0.86 0.84 0.82 0.84 0.86 0.91 (P₂O₅ + R₂O)/(M₂O₃) 1.38 1.39 1.39 1.40 1.38 1.38 1.34 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.60 1.55 1.58 1.62 1.56 1.53 1.46 in mol % SiO₂ in wt % 48.8 48.2 48.3 47.5 47.4 47.3 47.0 Al₂O₃ in wt % 22.9 23.4 23.1 23.3 23.8 24.0 24.6 P₂O₅ in wt % 12.5 12.7 12.7 12.8 12.5 12.5 12.5 Na₂O in wt % 13.7 14.2 14.0 14.2 14.4 14.6 14.6 MgO in wt % 1.9 1.4 1.7 2.0 1.7 1.4 1.1 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.421 2.419 2.420 2.426 2.426 2.424 2.420 Molar Volume 29.58 29.82 29.72 29.64 29.70 29.81 30.00 (cm³/mol) Strain Pt. (° C.) 615 616 616 615 615 623 624 Anneal Pt. (° C.) 666 671 670 666 669 679 681 Softening Pt. (° C.) 937.8 945.7 941.6 930.6 933.9 949.7 952.4 Temperature at 200 P 1655 1658 1658 1641 1646 1646 1657 Viscosity (° C.) Temperature at 35 kP 1235 1236 1236 1224 1233 1236 1246 Viscosity (° C.) Temperature at 160 1152 1154 1154 1141 1151 1152 1162 kP Viscosity (° C.) Liquidus Temperature (° C.) Liquidus Viscosity (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical 3.021 3.007 3.015 Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 763 743 764 760 760 748 748 temperature (° C.) 410° C. 1 hr Compressive Stress (MPa) 410° C. 1 hr Depth of Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 925 925 927 978 981 975 983 Compressive Stress (MPa) 410° C. 2 hr Depth of 43 45 44 40 40 41 41 Layer (mm) 410° C. 2 hr Vickers 20-30 30-40 20-30 >30 >30 >30 >30 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 3.3E−10 3.6E−10 3.4E−10 2.8E−10 2.8E−10 3.0E−10 3.0E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 135 136 137 138 139 140 141 SiO₂ in mol % 57.8 58.8 55.8 55.9 55.8 57.8 56.9 Al₂O₃ in mol % 17.0 16.5 17.0 18.0 18.1 17.0 16.9 P₂O₅ in mol % 6.4 6.4 7.6 7.7 7.7 6.6 7.0 Na₂O in mol % 16.6 16.2 17.3 16.2 16.7 17.2 17.0 MgO in mol % 2.0 2.0 0.1 0.1 0.1 0.1 0.1 ZnO in mol % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in mol % 0.0 0.0 2.0 2.0 1.5 1.2 2.0 (M₂O₃)/R_(x)O in mol % 0.91 0.90 0.88 0.98 0.99 0.92 0.88 (P₂O₅ + R₂O)/(M₂O₃) 1.36 1.37 1.46 1.33 1.35 1.40 1.43 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.48 1.49 1.59 1.45 1.44 1.48 1.55 in mol % SiO₂ in wt % 48.0 49.0 45.5 45.2 45.1 47.6 46.7 Al₂O₃ in wt % 23.9 23.3 23.5 24.7 24.8 23.8 23.5 P₂O₅ in wt % 12.6 12.6 14.7 14.8 14.8 12.8 13.6 Na₂O in wt % 14.2 13.9 14.5 13.5 13.9 14.6 14.4 MgO in wt % 1.1 1.1 0.1 0.1 0.0 0.0 0.1 ZnO in wt % 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.1 0.1 0.2 0.2 0.2 0.2 0.2 CaO in wt % 0.0 0.0 1.5 1.5 1.1 0.9 1.5 Compositional XRF XRF XRF XRF XRF XRF XRF analysis Density (g/cm³) 2.416 2.410 2.421 2.429 2.419 2.423 2.427 Molar Volume 29.96 29.93 30.46 30.56 30.71 30.09 30.16 (cm³/mol) Strain Pt. (° C.) 619 620 623 607 620 622 615 Anneal Pt. (° C.) 676 677 680 660 676 679 669 Softening Pt. (° C.) 948.8 957.8 947.1 916.9 944.6 946.4 928 Temperature at 200 P 1673 1684 1638 1652 1650 1674 1656 Viscosity (° C.) Temperature at 35 kP 1254 1261 1214 1238 1242 1248 1230 Viscosity (° C.) Temperature at 160 1171 1176 1130 1156 1157 1163 1147 kP Viscosity (° C.) Liquidus Temperature (° C.) Liquidus Viscosity (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 754 755 730 753 750 749 753 temperature (° C.) 410° C. 1 hr Compressive Stress (MPa) 410° C. 1 hr Depth of Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 953 922 895 898 896 925 906 Compressive Stress (MPa) 410° C. 2 hr Depth of 42 42 45 38 43 45 45 Layer (mm) 410° C. 2 hr Vickers >30 >30 >30 >30 >30 >30 >30 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 3.1E−10 3.1E−10 3.6E−10 2.6E−10 3.3E−10 3.6E−10 3.6E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr Example Number 142 143 144 145 SiO₂ in mol % 57.5 58.1 58.2 58.4 Al₂O₃ in mol % 16.7 16.0 16.0 16.0 P₂O₅ in mol % 6.9 6.2 6.2 6.2 Na₂O in mol % 16.7 16.0 16.1 16.1 MgO in mol % 0.1 3.6 3.4 3.1 ZnO in mol % 0.0 0.0 0.0 0.0 SnO₂ in mol % 0.1 0.1 0.1 0.1 CaO in mol % 2.0 0.1 0.0 0.0 (M₂O₃)/R_(x)O in mol % 0.89 0.81 0.82 0.83 (P₂O₅ + R₂O)/(M₂O₃) 1.42 1.39 1.40 1.40 in mol % (P₂O₅ + R_(x)O)/(M₂O₃) 1.54 1.62 1.61 1.59 in mol % SiO₂ in wt % 47.3 48.8 48.9 49.0 Al₂O₃ in wt % 23.3 22.8 22.8 22.8 P₂O₅ in wt % 13.5 12.4 12.3 12.3 Na₂O in wt % 14.2 13.9 14.0 14.0 MgO in wt % 0.1 2.0 1.9 1.7 ZnO in wt % 0.0 0.0 0.0 0.0 SnO₂ in wt % 0.2 0.1 0.1 0.1 CaO in wt % 1.5 0.0 0.0 0.0 Compositional XRF XRF XRF XRF analysis Density (g/cm³) 2.425 2.422 2.421 2.418 Molar Volume 30.12 29.52 29.54 29.61 (cm³/mol) Strain Pt. (° C.) 615 621 619 616 Anneal Pt. (° C.) 669 672 671 670 Softening Pt. (° C.) 930.1 938.5 938.9 941.3 Temperature at 200 P 1655 1652 1662 1664 Viscosity (° C.) Temperature at 35 kP 1232 1232 1240 1243 Viscosity (° C.) Temperature at 160 1147 1148 1157 1159 kP Viscosity (° C.) Liquidus Temperature (° C.) Liquidus Viscosity (P) Zircon Breakdown Temperature (° C.) Zircon Breakdown Viscosity (P) Stress Optical Coefficient ((nm · Mpa⁻¹ · mm⁻¹) Approximate Fictive 750 765 772 770 temperature (° C.) 410° C. 1 hr Compressive Stress (MPa) 410° C. 1 hr Depth of Layer (mm) 410° C. 1 hr Vickers Crack Initiation Load (kgf) 410° C. 2 hr 902 961 953 948 Compressive Stress (MPa) 410° C. 2 hr Depth of 48 40 42 41 Layer (mm) 410° C. 2 hr Vickers >30 >30 >30 >30 Crack Initiation Load (kgf) 410° C. 3 hr Compressive Stress (MPa) 410° C. 3 hr Depth of Layer (mm) 410° C. 4 hr Compressive Stress (MPa) 410° C. 4 hr Depth of Layer (mm) 410° C. 4 hr Vickers Crack Initiation Load (kgf) 410° C. 8 hr Compressive Stress (MPa) 410° C. 8 hr Depth of Layer (mm) D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 1 hr D FSM DOL 4.1E−10 2.8E−10 3.1E−10 3.0E−10 ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 2 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 3 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 4 hr D FSM DOL ~1.4 * 2 * (Dt){circumflex over ( )}0.5 at 410° C. 8 hr

Ion exchange is widely used to chemically strengthen glass articles for use in consumer electronics, automotive applications, appliances, architectural components, and other areas where high levels of damage resistance are desirable. In the ion exchange process, a glass article containing a first metal ion (e.g., alkali cations in Li₂O, Na₂O, etc.) is at least partially immersed in or otherwise contacted with an ion exchange bath or medium containing a second metal ion that is either larger or smaller than the first metal ion that is present in the glass. The first metal ions diffuse from the glass surface into the ion exchange bath/medium while the second metal ions from the ion exchange bath/medium replace the first metal ions in the glass to a depth of layer below the surface of the glass. The substitution of larger ions for smaller ions in the glass creates a compressive stress at the glass surface, whereas substitution of smaller ions for larger ions in the glass typically creates a tensile stress at the surface of the glass. In some embodiments, the first metal ion and second metal ion are monovalent alkali metal ions. However, other monovalent metal ions such as Ag⁺, Tl⁺, Cu⁺, and the like may also be used in the ion exchange process. In those instances where at least one of Ag⁺ and Cu⁺ is exchanged for metal ions in the glass, such glasses may be particularly useful for anti-viral and/or anti-microbial applications.

A cross-sectional view of a portion (i.e., ends of the glass sheet are not shown) of a glass sheet strengthened by ion exchange is schematically shown in FIG. 1. In the non-limiting example shown in FIG. 1, strengthened glass sheet 100 has a thickness t, central portion 130, and a first surface 110 and second surface 112 that are substantially parallel to each other. Compressive layers 120, 122 extend from first surface 110 and second surface 112, respectively, to depths of layer d₁, d₂ below each surface. Compressive layers 120, 122 are under a compressive stress, while central portion 130 is under a tensile stress, or in tension. The tensile stress in central portion 130 balances the compressive stresses in compressive layers 120, 122, thus maintaining equilibrium within strengthened glass sheet 100. In some embodiments, the glasses and glass articles described herein may be ion exchanged to achieve a compressive stress of at least about 300 MPa and/or a depth of compressive layer of at least about 10 nm. In some embodiments, the glasses and glass articles described herein may be ion exchanged to achieve a compressive stress of at least about 500 MPa and/or a depth of compressive layer of at least about 40 nm. In some embodiments, the glass is ion exchanged to achieve a compressive stress of at least about 200, 300, 400, 500, 600, 700, 800, 900, or 1000 MPa. In some embodiments, the glass is ion exchanged to achieve a depth of layer of at least about 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, or 110 nm or more.

In addition to high damage resistance, the glasses described herein may be ion exchanged to achieve desired levels of compressive stress and compressive depth of layer in relatively short times. Following ion exchange at 410° C. for 4 hours in molten KNO₃ salt, for example, a compressive layer having a compressive stress of greater than about 700 MPa and a depth of compressive layer of greater than about 75 nm may be achieved in these glasses. In some embodiments, the ion exchange is done at about 400° C., 410° C., 420° C., 430° C., 440° C., 450° C., 460° C., 470° C., 480° C., 490° C., 500° C., 510° C., 520° C., 530° C., 540° C., or 550° C. or greater. In some embodiments, the ion exchange is done for about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 hours.

FIG. 2 is a plot of depth of layer as a function of compressive stress for samples a-f in Table 1. The 0.7 mm thick samples were annealed at 700° C. and ion exchanged in a molten KNO₃ salt bath at 410° C. for times ranging from 1 hour up to 8 hours (groups “b-d” in FIG. 2) or at 470° C. for six minutes (group “a” in FIG. 2). The samples that were ion exchanged at 470° C. for six minutes exhibited compressive stresses and depths of layer that are well below the frangibility limit (i.e., the point at which the glass sample should or is likely to exhibit frangible behavior, indicated by line 1 in FIG. 2). The ion exchange time required for 0.7 mm thick samples to reach the frangibility limit is slightly greater than one hour at 410° C. In samples having higher fictive temperatures with viscosities corresponding to about 10¹¹ Poise (i.e., unannealed, as down-drawn samples), the frangibility limit will also be met in a similarly short time, but the compressive stress will be lower and the depth of layer will be greater than in annealed samples. Samples that were ion exchanged for one hour (group “b”) exhibited compressive stresses and depths of layer that are just below the frangibility limit, and samples that were ion exchanged for either 4 or 8 hours (groups “c” and “d”, respectively) exhibit compressive stresses and depths of layer that exceed the frangibility limit.

The ability to ion exchange the glasses described herein may be at least partially attributable to the fact that these glasses have potassium and sodium interdiffusion coefficients that are significantly greater that those of other alkali aluminosilicate glasses that are used in applications in which damage resistance, as characterized by the Vickers crack initiation threshold of the glass, is a desirable attribute. At 410° C., the glasses described herein have a potassium/sodium interdiffusion coefficient of at least about 2.4×10⁻¹⁰ cm²/s, 3.0×10⁻¹⁰ cm²/s, 4.0×10⁻¹⁰ cm²/s, or 4.5×10⁻¹⁰ cm²/s, 6.0×10⁻¹⁰ cm²/s, 7.5×10⁻¹⁰ cm²/s, 9.0×10⁻¹⁰ cm²/s, 1.0×10⁻⁹ cm²/s, 1.2×10⁻⁹ cm²/s, 1.5×10⁻⁹ cm²/s and in some embodiments, in a range from about 2.4×10⁻¹⁰ cm⁻²/s, 3.0×10⁻¹⁰ cm²/s, 4.0×10⁻¹⁰ cm²/s, or 4.5×10⁻¹⁰ cm²/s up to about 7.5×10⁻¹⁰ cm²/s, 9.0×10⁻¹⁰ cm²/s, 1.0×10⁻⁹ cm²/s, 1.2×10⁻⁹ cm²/s, or 1.5×10⁻⁹ cm²/s. In contrast to these glasses, the alkali aluminosilicate glasses described in U.S. patent application Ser. Nos. 12/858,490, 12/856,840, and 12/392,577 have potassium/sodium interdiffusion coefficients of less than 1.5×10⁻¹⁰ cm²/s.

An embodiment comprises an alkali aluminosilicate glass comprising at least about 4 mol % P₂O₅, wherein [M₂O₃ (mol %)/R_(x)O (mol %)]<1.4, where M₂O₃=Al₂O₃+B₂O₃ and R_(x)O is the sum of monovalent and divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, [M₂O₃ (mol %)/R_(x)O (mol %)]<1. In some embodiments, the alkali aluminosilicate glass further comprises less than 1 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises less than 1 mol % B₂O₃. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % B₂O₃. In some embodiments, the monovalent and divalent cation oxides are selected from the group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO. In some embodiments, the alkali aluminosilicate glass has a potassium/sodium interdiffusion coefficient of at least about 2.4×10⁻¹⁰ cm²/s at 410° C. In some embodiments, the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁰ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C.

An embodiment comprises an alkali aluminosilicate glass comprising 0.6<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.4 where M₂O₃=Al₂O₃+B₂O₃ and R_(x)O is the sum of monovalent and divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, 0.8<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.4. In some embodiments, 0.8≦[M₂O₃ (mol %)/R_(x)O (mol %)]≦1.0. In some embodiments, the alkali aluminosilicate glass further comprises less than 1 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises less than 1 mol % B₂O₃. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % B₂O₃. In some embodiments, the monovalent and divalent cation oxides are selected from the group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO. In some embodiments, the alkali aluminosilicate glass has a potassium/sodium interdiffusion coefficient of at least about 2.4×10⁻¹⁰ cm²/s at 410° C. In some embodiments, the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁰ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C.

Another embodiment comprises an alkali aluminosilicate glass comprising at least about 4% P₂O₅, wherein the alkali aluminosilicate glass is ion exchanged to a depth of layer of at least about 20 μm, and wherein 0.6<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.4, where M₂O₃=Al₂O₃+B₂O₃ and R_(x)O is the sum of monovalent and divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, 0.6<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.0. In some embodiments, 0.8<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.4. In some embodiments, 0.8≦[M₂O₃ (mol %)/R_(x)O (mol %)]≦1.0. In some embodiments, the alkali aluminosilicate glass further comprises less than 1 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises less than 1 mol % B₂O₃. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % B₂O₃. In some embodiments, the monovalent and divalent cation oxides are selected from the group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO. In some embodiments, the alkali aluminosilicate glass has a potassium/sodium interdiffusion coefficient of at least about 2.4×10⁻¹⁰ cm²/s at 410° C. In some embodiments, the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁰ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C.

Another embodiment comprises an alkali aluminosilicate glass comprising at least about 4% P₂O₅, wherein 1.3<[(P₂O₅+R₂O)/M₂O₃]≦2.3, where M₂O₃=Al₂O₃+B₂O₃ and R₂O is the sum of monovalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, the alkali aluminosilicate glass further comprises less than 1 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises less than 1 mol % B₂O₃. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % B₂O₃. In some embodiments, the monovalent and divalent cation oxides are selected from the group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO. In some embodiments, the alkali aluminosilicate glass has a potassium/sodium interdiffusion coefficient of at least about 2.4×10⁻¹⁰ cm²/s at 410° C. In some embodiments, the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁹ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C.

In some embodiments, the alkali aluminosilicate glass comprises from about 40 mol % to about 70 mol % SiO₂; from about 11 mol % to about 25 mol % Al₂O₃; from about 4 mol % to about 15 mol % P₂O₅; and from about 13 mol % to about 25 mol % Na₂O. In some embodiments, the alkali aluminosilicate glass comprises from about 50 mol % to about 65 mol % SiO₂; from about 14 mol % to about 20 mol % Al₂O₃; from about 4 mol % to about 10 mol % P₂O₅; and from about 14 mol % to about 20 mol % Na₂O. In some embodiments, the alkali aluminosilicate glass further comprises less than 1 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises less than 1 mol % B₂O₃. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % B₂O₃. In some embodiments, the monovalent and divalent cation oxides are selected from the group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO.

In some embodiments, the alkali aluminosilicate glasses described above are ion exchanged to a depth of layer of at least about 20 μm. In some embodiments, the glasses are ion exchanged to a depth of layer of at least about 40 μm. In some embodiments, the alkali aluminosilicate glasses have a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least 500 MPa. In some embodiments, the compressive stress is at least 750 MPa. In some embodiments, the compressive stress layer is from about 500 MPa to about 2000 MPa. In some embodiments, the ion exchanged alkali aluminosilicate glasses have a Vickers indentation crack initiation load of at least about 8 kgf. In some embodiments, the ion exchanged alkali aluminosilicate glasses have a Vickers indentation crack initiation load of at least about 12 kgf.

An embodiment comprises a method of strengthening an alkali aluminosilicate glass, the method comprising: providing an alkali aluminosilicate glass as described above, and immersing the alkali aluminosilicate glass in an ion exchange bath for a time period of up to about 24 hours to form a compressive layer extending from a surface of the alkali aluminosilicate glass to a depth of layer of at least 20 μm. In some embodiments, the alkali aluminosilicate glass comprises at least about 4 mol % P₂O₅, wherein [M₂O₃ (mol %)/R_(x)O (mol %)]<1.4, where M₂O₃=Al₂O₃+B₂O₃ and R_(x)O is the sum of monovalent and divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, [M₂O₃ (mol %)/R_(x)O (mol %)]<1. In some embodiments, the alkali aluminosilicate glass comprises 0.6<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.4 where M₂O₃=Al₂O₃+B₂O₃ and R_(x)O is the sum of monovalent and divalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, 0.8<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.4. In some embodiments, 0.8<[M₂O₃ (mol %)/R_(x)O (mol %)]<1.0. In some embodiments, the alkali aluminosilicate glass comprising at least about 4% P₂O₅, wherein 1.3<[(P₂O₅+R₂O)/M₂O₃]≦2.3, where M₂O₃=Al₂O₃+B₂O₃ and R₂O is the sum of monovalent cation oxides present in the alkali aluminosilicate glass. In some embodiments, the alkali aluminosilicate glass comprises from about 40 mol % to about 70 mol % SiO₂; from about 11 mol % to about 25 mol % Al₂O₃; from about 4 mol % to about 15 mol % P₂O₅; and from about 13 mol % to about 25 mol % Na₂O. In some embodiments, the alkali aluminosilicate glass comprises from about 50 mol % to about 65 mol % SiO₂; from about 14 mol % to about 20 mol % Al₂O₃; from about 4 mol % to about 10 mol % P₂O₅; and from about 14 mol % to about 20 mol % Na₂O. In some embodiments, the alkali aluminosilicate glass further comprises less than 1 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % K₂O. In some embodiments, the alkali aluminosilicate glass comprises less than 1 mol % B₂O₃. In some embodiments, the alkali aluminosilicate glass comprises 0 mol % B₂O₃. In some embodiments, the monovalent and divalent cation oxides are selected from the group consisting of Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO.

In some embodiments, the alkali aluminosilicate glasses described above are ion exchanged to a depth of layer of at least about 20 μm. In some embodiments, the glasses are ion exchanged to a depth of layer of at least about 40 μm. In some embodiments, the alkali aluminosilicate glasses have a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least 500 MPa. In some embodiments, the compressive stress is at least 750 MPa. In some embodiments, the compressive stress layer is from about 500 MPa to about 2000 MPa. In some embodiments, the ion exchanged alkali aluminosilicate glasses have a Vickers indentation crack initiation load of at least about 8 kgf. In some embodiments, the ion exchanged alkali aluminosilicate glasses have a Vickers indentation crack initiation load of at least about 12 kgf.

While typical embodiments have been set forth for the purpose of illustration, the foregoing description should not be deemed to be a limitation on the scope of the disclosure or appended claims. Accordingly, various modifications, adaptations, and alternatives may occur to one skilled in the art without departing from the spirit and scope of the present disclosure or appended claims. 

The invention claimed is:
 1. An alkali aluminosilicate glass comprising at least about 4 mol % P₂O₅ and from 0 mol % to about 4 mol % B₂O₃, wherein the alkali aluminosilicate glass is lithium-free and ion exchanged to a depth of layer of at least about 10 μm, and wherein: i. 1.3<[(P₂O₅+R₂O)/M₂O₃]≦2.3; where M₂O₃=Al₂O₃+B₂O₃, and R₂O is the sum of monovalent cation oxides present in the alkali aluminosilicate glass.
 2. The alkali aluminosilicate glass of claim 1, wherein the glass satisfies: 1.5<[(P₂O₅+R₂O)/M₂O₃]≦2.0.
 3. The alkali aluminosilicate glass of claim 1, wherein the glass comprises less than 1 mol % K₂O.
 4. The alkali aluminosilicate glass of claim 1, wherein the glass comprises less than 1 mol % B₂O₃.
 5. The alkali aluminosilicate glass of claim 1, wherein the alkali aluminosilicate glass has a potassium/sodium interdiffusion coefficient of at least about 2.4×10⁻¹⁰ cm²/s at 410° C.
 6. The alkali aluminosilicate glass of claim 4, wherein the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁰ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C.
 7. The alkali aluminosilicate glass of claim 1, wherein the glass has a compressive layer extending from a surface of the glass to the depth of layer, and wherein the compressive layer is under a compressive stress of at least about 300 MPa.
 8. The alkali aluminosilicate glass of claim 1, wherein the ion exchanged glass has a Vickers indentation crack initiation load of at least about 7 kgf.
 9. The alkali aluminosilicate glass of claim 8, wherein the ion exchanged glass has a Vickers indentation crack initiation load of at least about 12 kgf.
 10. The alkali aluminosilicate glass of claim 1, wherein the monovalent and divalent cation oxides are selected from the group consisting of Na₂O, K₂O, Rb₂O, Cs₂O, MgO, CaO, SrO, BaO, and ZnO.
 11. The alkali aluminosilicate glass of claim 1, wherein the alkali aluminosilicate glass comprises from about 40 mol % to about 70 mol % SiO₂; from about 11 mol % to about 25 mol % Al₂O₃; from about 4 mol % to about 15 mol % P₂O₅; and from about 13 mol % to about 25 mol % Na₂O.
 12. The alkali aluminosilicate glass of claim 11, wherein the alkali aluminosilicate glass comprises from about 50 mol % to about 65 mol % SiO₂; from about 14 mol % to about 20 mol % Al₂O₃; from about 4 mol % to about 10 mol % P₂O₅; and from about 14 mol % to about 20 mol % Na₂O.
 13. The alkali aluminosilicate glass of claim 11, wherein the alkali aluminosilicate glass wherein the glass comprises less than 1 mol % K₂O.
 14. The alkali aluminosilicate glass of claim 11, wherein the alkali aluminosilicate glass wherein the glass comprises less than 1 mol % B₂O₃.
 15. The alkali aluminosilicate glass of claim 11, wherein the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁰ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C.
 16. A method of forming an ion-exchanged alkali aluminosilicate glass, the method comprising: a. providing a non-ion exchanged alkali aluminosilicate precursor glass comprising at least about 4 mol % P₂O₅ and from 0 mol % to about 4 mol % B₂O₃, wherein the precursor glass is lithium-free and wherein 1.3<[P₂O₅+R₂O)/M₂O₃]≦2.3, where M₂O₃=Al₂O₃+B₂O₃, and R₂O is the sum of monovalent cation oxides present in the precursor glass, and b. immersing the precursor glass in an ion exchange bath for a time period of up to about 24 hours to form an ion-exchanged alkali aluminosilicate glass having a compressive layer extending from a surface of the ion-exchanged alkali aluminosilicate glass to a depth of layer of at least 10 μm.
 17. The method of claim 16, wherein the precursor glass satisfies, 1.5<[(P₂O₅+R₂O)/M₂O₃]≦2.0.
 18. The method of claim 16, wherein the ion-exchanged alkali aluminosilicate glass comprises less than 1 mol % K₂O.
 19. The method of claim 16, wherein the ion-exchanged alkali aluminosilicate glass comprises less than 1 mol % B₂O₃.
 20. The method of claim 16, wherein the compressive layer is under a compressive stress of at least about 300 MPa.
 21. The method of claim 16, wherein the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 7 kgf.
 22. The method of claim 21, wherein the ion exchanged alkali aluminosilicate glass has a Vickers indentation crack initiation load of at least about 12 kgf.
 23. An alkali aluminosilicate glass consisting essentially of from about 40 mol % to about 70 mol % SiO₂; from about 11 mol % to about 25 mol % Al₂O₃; from about 4 mol % to about 15 mol % P₂O₅; from about 13 mol % to about 25 mol % Na₂O; from about 13 to about 30 mol % R_(x)O; from about 11 to about 30 mol % M₂O₃; from 0 mol % to about 1 mol % K₂O; from 0 mol % to about 4 mol % B₂O₃, and 3 mol % or less of one or more of TiO₂, MnO, Nb₂O_(s), MoO₃, Ta₂O₅, WO₃, ZrO₂, Y₂O₃, La₂O₃, HfO₂, CdO, SnO₂, Fe₂O₃, CeO₂, As₂O₃, Sb₂O₃, Cl, and Br; wherein i. R_(x)O is the sum of the alkali metal oxides, alkaline earth metal oxides, and transition metal monoxides present in the glass, ii. the glass is lithium-free; iii. the glass is ion exchanged to a depth of layer of at least about 10 μm, and iv. 1.3<[(P₂O₅+R₂O)/M₂O₃]≦2.3; where M₂O₃=Al₂O₃+B₂O₃, and R₂O is the sum of monovalent cation oxides present in the glass.
 24. The alkali aluminosilicate glass of claim 23, wherein the glass comprises from about 50 mol % to about 65 mol % SiO₂; from about 14 mol % to about 20 mol % Al₂O₃; from about 4 mol % to about 10 mol % P₂O₅; and from about 14 mol % to about 20 mol % Na₂O.
 25. The alkali aluminosilicate glass of claim 24, wherein the glass wherein the glass comprises less than 1 mol % B₂O₃.
 26. The alkali aluminosilicate glass of claim 23, wherein the potassium/sodium interdiffusion coefficient is in a range from about 2.4×10⁻¹⁰ cm²/s up to about 1.5×10⁻⁹ cm²/s at 410° C. 